The use of a curved ophthalmic blade to facilitate incising Mohs micrographic sections with the desired bevel despite anatomic obstructions

To establish whether nitric-oxide (NO) participates in the regulation of prolactin (PRL) secretion in humans in basal conditions and/or under stimulation with vasoactive intestinal polypeptide (VIP), seven normal men were treated with a placebo (normal saline) or the NO synthase (NOS) inhibitor L-NAME (40 microg/kg injected plus 50 microg/kg infused intravenously over 60 minutes), which in previous studies has been found able to modify other pituitary hormone secretions. Experiments were performed either in basal conditions or during stimulation of PRL secretion with an intravenous infusion of VIP (4 pmol/kg min over 60 minutes). The administration of L-NAME was unable to change the basal secretion of PRL. In contrast, L-NAME significantly enhanced the PRL increase induced by VIP. These data argue against an involvement of NO in regulation of basal PRL secretion. In contrast, the stimulatory effect of L-NAME on VIP-induced PRL secretion suggests that NO exerts an inhibitory control of the PRL response to VIP.     

Stereotyped yawning responses induced by electrical and chemical stimulation of paraventricular nucleus of the rat

Yawning was evoked by electrical or chemical stimulation in the paraventricular nucleus (PVN) of anesthetized, spontaneously breathing rats. To evaluate physiological aspects of yawning, we monitored polygraphic measures as follows; a coordinated motor pattern of yawning was assessed by monitoring breathing [intercostal electromyogram (EMG)], mouth opening (digastric EMG), and stretching of the trunk (back EMG). We also recorded blood pressure (BP), heart rate, and the electrocorticogram (ECoG) to evaluate autonomic function and arousal responses during yawning. A stereotyped yawning response was reproducibly evoked by electrical stimulation or microinjection of -glutamate or NOC-7, a nitric oxide (NO)-releasing compound, into the PVN. The stereotyped yawning response consisted of two sequential events, an initial response represented a depressor response and an arousal shift in the ECoG to lower voltage and faster rhythms. These initial changes were followed by a yawning behavior characterized by a single large inspiration with mouth opening and stretching of the trunk. A similar sequence of events occurred during spontaneous yawning; a fall in BP and ECoG arousal preceded a yawning behavior. An increase in the frequency of spontaneous yawns was also observed after microinjection of -glutamate or NOC-7 into the PVN. Intravenous administration of NG-monomethyl--arginine, an inhibitor of nitric oxide synthase (NOS), prevented the stereotyped yawning response evoked by chemical stimulation of the PVN. Histological examination revealed that effective sites for the yawning responses were located in the medial part of the rostral PVN, the site of parvocellular and magnocellular neurons. NADPH-diaphorase histochemistry showed the existence of NOS-containing cells in yawning-evoked sites of the PVN. In summary, the sequential events of yawning may be generated by NOS-containing parvocellular neurons in the medial part of the rostral PVN projecting to the lower brain stem.     

Diinosine polyphosphates, a group of dinucleotides with antagonistic effects on diadenosine polyphosphate receptor

Nitric oxide synthase, an enzyme responsible for nitric oxide (NO) formation has been found in the hypothalamic paraventricular nucleus and median eminence, structures closely associated with regulation of the pituitary activity, and the pituitary gland itself. Nitric oxide modulates the stimulated release of CRH from the rat hypothalamus in vitro, which suggests its role in regulating the secretion of ACTH from the pituitary corticotrops and of corticosterone from the adrenal cortex. The purpose of the present study was to elucidate the yet unknown role of endogenous NO in the HPA response to central cholinergic stimulation in conscious rats. Neither L-arginine an NO precursor, nor the NO synthase blockers N omega-nitro-L-arginine methyl ester (L-NAME) and N omega-nitro-L-arginine (L-NNA) caused any consistent changes in the basal serum corticosterone levels. L-arginine, given in higher doses (120-150 mg/kg ip) 15 min prior to icv carbachol (2 micrograms), markedly diminished the carbachol-induced rise in corticosterone secretion. Systemic pretreatment with the nitric oxide synthase inhibitor L-NAME (5 mg/kg) significantly raised the carbachol-elicited corticosterone response, while addition of L-arginine completely blocked the effect of L-NAME. A similar increase in the carbachol-induced corticosterone response was produced by icv pretreatment with L-NAME (2 micrograms), indicating a central site of the NO interaction with cholinergic stimulation of the HPA response. L-NAME is a weak inhibitor of neuronal NOS itself, and must first be de-estrified to N omega-nitro-L-arginine to potently inhibit this enzyme. Systemic (10 mg/kg) and icv (1 microgram) pretreatment with L-NNA enhanced more effectively the carbachol-induced rise in corticosterone secretion than did pretreatment with L-NAME by either route. These results are the first direct evidence that endogenous NO significantly inhibits the HPA response to central cholinergic, muscarinic receptor stimulation under in vivo conditions.     

Role of endogenous nitric oxide in allergen-induced airway responses in guinea-pigs

1. Endogenous nitric oxide (NO) can be detected in exhaled air and accumulates in inflamed airways. However its physiological role has not been fully elucidated. In this study, we investigated a role for endogenous NO in allergen-induced airway responses. Sensitised guinea-pigs were treated with NG-nitro-L-arginine methyl ester L-NAME (2.0 mM) or aminoguanidine (AG) (2.0 mM) 30 min before the allergen challenge, and 3 and 4 h after the challenge. Alternatively, L-arginine (2.4 mM) treatment was performed 30 min before, and 2 and 3 h after the challenge. In all groups, ovalbumin (OVA) challenge (2 mg ml(-1) for 2 min) was performed, and airway responses, NO production, infiltration of inflammatory cells, plasma exudation and histological details were examined. 2. Allergen-challenged animals showed an immediate airway response (IAR) and a late airway response (LAR), which synchronised with an increase in exhaled NO. Treatment with L-NAME and AG did not affect IAR while they significantly blocked LAR (72% and 80% inhibition compared to vehicle) and production of NO (35% and 40% inhibition). On the other hand, treatment with L-arginine did not affect IAR but potentiated LAR (74% augmentation). 3. In bronchoalveolar lavage (BAL) fluid, allergen-induced increases in eosinophils were reduced by 48% for L-NAME treatment compared to vehicle, and increased by 56% for L-arginine treatment. 4. Treatment with L-NAME significantly decreased airway microvascular permeability to both Monastral blue (MB) and Evans blue (EB) dye (50.6% and 44% inhibition). 5. We conclude that allergen-induced LAR is closely associated with NO production, and that NO plays a critical role in inflammatory cell infiltration and plasma exudation in the allergic condition.     

Cigarette smoke-inhibition of neurogenic bronchoconstriction in guinea-pigs in vivo: involvement of exogenous and endogenous nitric oxide

1. We investigated the effect of acute inhalation of cigarette smoke on subsequent non-adrenergic, non-cholinergic (NANC) neural bronchoconstriction in anaesthetized guinea-pigs in vivo by use of pulmonary insufflation pressure (PIP) as an index of airway tone. The contribution of endogenous nitric oxide (NO) was investigated with the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). The contribution of plasma exudation to the response was investigated with Evans blue dye as a plasma marker. 2. Inhalation of 50 tidal volumes of cigarette smoke or air had no significant effect on baseline PIP. In the presence of propranolol and atropine (1 mg kg(-1) each), electrical stimulation of the vagus nerves in animals given air 30 min previously induced a frequency-dependent increase in PIP above sham stimulated controls (16 fold increase at 2.5 Hz, 24 fold increase at 10 Hz). In contrast, in smoke-exposed animals, the increase in subsequent vagally-induced PIP was markedly less than in the air controls (90% less at 2.5 Hz, 76% less at 10 Hz). 3. L-NAME (10 mg kg[-1]), given 10 min before air or smoke, potentiated subsequent vagally-induced (2.5 Hz) NANC bronchoconstriction by 338% in smoke-exposed animals, but had no significant effect in air-exposed animals. The inactive enantiomer D-NAME (10 mg kg[-1]) had no effect, and the potentiation by L-NAME was partially reversed by the NO-precursor L-arginine (100 mg kg[-1]). Vagal stimulation did not affect the magnitude of vagally-induced bronchoconstriction 30 min later. 4. Cigarette smoke exposure reduced the magnitude of subsequent bronchoconstriction induced by neurokinin A (NKA) by 37% compared with the effect of NKA in air-exposed animals. L-NAME had no significant effect on the smoke-induced inhibition of NKA-induced bronchoconstriction. 5. Vagally-induced plasma exudation in the main bronchi was greater in smoke-exposed animals compared with air-exposed animals (120% greater at 2.5 Hz, 82% greater at 10 Hz). 6. We conclude that cigarette smoke-induced inhibition of subsequent NANC neurogenic bronchoconstriction is not associated with inhibition of airway plasma exudation and is mediated in part via exogenous smoke-derived NO, or another bronchoprotective molecule, and by endogenous NO.     

The value of a single skin prick testing for specific IgE Dermatophagoides pteronyssinus to distinguish atopy from non-atopic asthmatic children in the tropics

Recently, evidence has been presented that nitric oxide (NO) modulates myocardial contraction induced by beta-adrenergic stimulation in vitro and in vivo. In this study, we investigated whether inhibition of the L-arginine NO system augments the positive inotropic response of the left ventricle to direct stimulation of the sympathetic nerves in vivo in the dog. Electrical stimulation was applied to the left stellate ganglion (LSG) for 1 min at submaximal (5 V, 2.5, 5 and 10 Hz) and supramaximal intensities (10 V, 10 Hz) in twelve anesthetized and vagotomized dogs. Next, in the same dogs, N(omega)-nitro L-arginine methylester (L-NAME) was infused into the left anterior descending (LAD) coronary artery, and LSG stimulation repeated using the same protocol. Finally, L-arginine was infused into the LAD artery, and LSG stimulation repeated. We used the maximum of the first derivative of left ventricular pressure (LV max d P/dt) as an index of the myocardial contractility. Plasma epinephrine and norepinephrine concentrations were measured in the coronary sinus at 5 V, 2.5 Hz before and after L-NAME treatment in five of twelve dogs. L-NAME treatment significantly augmented the inotropic response of the left ventricle (percent change in the LV max dP/dt) to LSG submaximal stimulation trains from 164 +/- 13 to.212 +/- 21 (P < 0.03), from 187 +/- 15 to 234 +/- 25 (P < 0.05) and from 220 +/- 19 to 280 +/- 33% (P < 0.05), respectively. This response was reversed by L-arginine treatment. However, the inotropic response to the supramaximal stimulation train did not change after L-NAME and L-arginine treatment. L-NAME significantly increased plasma norepinephrine concentration from 0.69 +/- 0.41 to 1.00 +/- 0.52 ng/ml without changing plasma epinephrine concentration in the coronary sinus. It is concluded that the inhibition of the L-arginine NO system augmented the positive inotropic effect on the left ventricle during sympathetic nerve stimulation in normal dogs in vivo.     

NG-nitro-L-arginine methyl ester reduces senna- and cascara-induced diarrhoea and fluid secretion in the rat

Senna (60 mg/kg orally) and cascara (800 mg/kg orally)-induced diarrhoea and net fluid secretion were studied in rats for a time period of 1-8 h. NG-Nitro-L-arginine methyl ester (L-NAME) (2.5-25 mg/kg i.p. twice, 15 min before and 4 h after laxative administration), an inhibitor of nitric oxide synthase, reduced the diarrhoeal response. This effect was counteracted by L-arginine (600 and 1500 mg/kg i.p. 15 min before laxative administration), the precursor of nitric oxide (NO). The senna- and cascara-stimulated fluid secretion was reduced by NG-nitro-L-arginine methyl ester 25 mg/kg i.p. (twice, 15 min before and 4 h after laxative administration), while the stereoisomer NG-nitro-D-arginine methyl ester (D-NAME) 25 mg/kg i.p. was without effect. These results suggest a possible involvement of NO in senna- and cascara-induced diarrhoea and fluid secretion.     

The effect of hydroxyethyl starch on platelet aggregation in vitro

To elucidate the role of endogenous nitric oxide (NO) in allergen- (AIB) and hyperventilation-induced bronchoconstriction (HIB), the effects of an NO synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), on AIB and HIB were studied in guinea-pigs. In the AIB group, 21 anaesthetized guinea-pigs, actively sensitized with 1% ovalbumin, were challenged with aerosolized 0.1% ovalbumin solution under mechanical ventilation. In the HIB group, 14 guinea-pigs were challenged with hyperventilation (tidal volume of 12 mL x kg(-1) at 150 breaths x min(-1) with 21% O2 and 5% CO2 dry gas) for 5 min. In both groups, lung resistance (RL) was measured using a pressure-volume-sensitive body plethysmograph, with or without L-NAME pretreatment (8 mg x kg(-1) i.v. followed by 2 mg x kg(-1) x min(-1) i.v.). The NO precursor, L-arginine was injected at a rate of 15 mg x kg(-1) x min(-1) after L-NAME injection (10 mg x kg(-1)) in the AIB group. The results were as follows. In the AIB group, the maximal RL change was significantly potentiated by pretreatment with L-NAME. This potentiating effect of L-NAME was reversed by L-arginine. In the HIB group, the pretreatment with L-NAME had no effect on increases in RL. These findings suggest that endogenous nitric oxide may play an important role in the modulation of allergen-, but not hyperventilation-induced bronchoconstriction in guinea-pigs.     

Mediation by nitric oxide of TRH-, but not metoclopramide-stimulated TSH secretion in humans

In order to establish whether nitric oxide (NO) participates in the regulation of thyroid stimulating hormone (TSH) secretion in humans, seven normal men were treated with a placebo (normal saline) or the NO synthase inhibitor L-NAME, given at doses (40 micrograms kg-1 injected plus 50 micrograms kg-1 infused i.v.) previously found to be unable to change blood pressure. Experiments were carried out either in basal conditions or during stimulation of TSH secretion with an i.v. injection of 200 micrograms thyrotropin releasing hormone (TRH) or 10 mg of the dopaminergic antagonist metoclopramide (MCP). Administration of L-NAME did not change the basal secretion of TSH or the TSH response to MCP, but significantly reduced the TSH increase induced by TRH. These data fail to provide evidence of NO involvement in regulation of basal TSH secretion. NO also appears to be without effects on the dopaminergic control of TSH secretion. In contrast, the inhibitory effect of L-NAME on TRH-induced TSH secretion suggests the mediation by NO of the TSH-releasing action of TRH.     

NG-nitro-L-arginine methyl ester reduces necrotic but not apoptotic cell death induced by reversible focal ischemia in rat

During cerebral ischemia, nitric oxide (NO) production via stimulation of NO synthase, is likely one of the major events leading to neuronal death. Recently, we have demonstrated that after reversible focal ischemia, apoptosis was implicated in the penumbra whereas necrosis was prominent in the ischemic core. We have now examined the effect of a non-specific inhibitor of NO synthase, NG-nitro-L-arginine methyl ester (L-NAME, 3 ing kg-1 i.p., 5 min and 3 h after the onset of ischemia), on the progress of apoptotic and necrotic nuclei following transient focal cerebral ischemia, using DNA electrophoresis and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick-end labeling (TUNEL assay). Our results indicated that L-NAME prevented the loss of necrotic, but not apoptotic cells.     

Influence of a selective guanylate cyclase inhibitor, and of the contraction level, on nitrergic relaxations in the gastric fundus

1. The influence of the soluble guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ) on non-adrenergic non-cholinergic (NANC) relaxations and the possible role of a nerve-derived hyperpolarizing factor in NANC relaxation were investigated in the rat gastric fundus. 2. ODQ (10(-6) and 10(-5) M) concentration-dependently inhibited the short-lasting relaxations by NO (2 x 10(-6) M-10(-4) M) administered as a bolus without influencing the relaxation by 3 x 10(-8) M isoprenaline. The relaxation by an infusion of NO was reduced to the same extent by 10(-6) and 10(-5) M ODQ. 3. The electrically induced short-lasting and sustained relaxations (40 V, 1 ms, 0.5-16 Hz, 10 s trains at 2 min interval or cumulative increase in the frequency every 2 min) in NANC conditions were inhibited to a similar extent by 10(-6) and 10(-5) M ODQ, and by the NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME; 3 x 10(-4) M). 4. ODQ (10(-6) M) and L-NAME (3 x 10(-4) M), administered after 5, 10 or 20 min of long-term stimulation, reversed the relaxation to a similar extent (approximately 50% at 2 Hz and 20% at 8 Hz). 5. When the tissues were contracted to 40% of maximum by adapting the concentration of prostaglandin F2alpha (PGF2alpha), the inhibitory effect of 3 x 10(-4) M L-NAME on relaxations induced by train and cumulative stimulation was the same as when tissues were contracted with 3 x 10(-7) M PGF2alpha. 6. The findings of this study illustrate that the relaxation by exogenous and endogenous NO in the rat gastric fundus is due to activation of soluble guanylate cyclase. During long-term electrical stimulation, the partial contribution of NO to NANC relaxation is maintained but it is small at higher frequencies of stimulation. Evidence for the contribution of a nerve-derived hyperpolarizing factor to NANC relaxation was not obtained.     

Role of nitric oxide (NO) in ocular inflammation

1. The actions of nitric oxide (NO) have been investigated in the rabbit eye, with particular emphasis on the relationship between NO and C-fibres and on those effects of NO that may be of importance in the inflammatory response to C-fibre stimulation. 2. The NO synthase inhibitor, NG-nitro-L-arginine (L-NAME; 10-200 mg kg-1), but not the inactive analogue D-NAME (200 mg kg-1), was found to block the inflammatory response induced by infrared irradiation of the iris in a dose-dependent manner. The inhibitory effects of L-NAME (200 mg kg-1) were partially reversed by L-arginine (500 mg kg-1), but not by D-arginine (500 mg kg-1). 3. L-NAME (200 mg kg-1) virtually abolished the ocular effects of intravitreal injection of calcitonin gene-related peptide (CGRP) (0.3 nmol). 4. The concentration of CGRP in aqueous humour from untreated rabbit eyes was 0.1 +/- 0.001 nmol l-1. Irradiation of the iris raised the CGRP concentration to 8.9 +/- 1.5 nmol l-1. L-NAME (200 mg kg-1) greatly suppressed the irradiation-evoked release of CGRP, the concentration in the aqueous humour being 1.2 +/- 0.2 nmol l-1 (P < 0.001). L-Arginine reversed the L-NAME-induced inhibition of release of CGRP, the concentration of CGRP in the aqueous humour being 9.7 +/- 0.6 nmol l-1. 5. In addition, a NO donor, sodium nitroprusside (0.9 mumol), was found to raise the concentration of CGRP in the aqueous humour (14.8 +/- 0.8 nmol l-1) and to induce symptoms of ocular inflammation. The elevation in concentration of CGRP induced by sodium nitroprusside was not affected by L-NAME (200 mg kg-1) (14.5 +/- 1.2 nmol l-1). Ocular responses were not inhibited by L-NAME. 6. Our findings suggest that NO plays an important role in ocular inflammation by activating C-fibres (directly or indirectly) and by mediating CGRP-induced responses.     

Drinking and blood pressure responses to central injection of L-NAME in conscious rats

The drinking behavior and blood pressure responses to i.c.v. administration of artificial cerebrospinal fluid (aCSF) or NG-nitro-L-arginine methyl ester (L-NAME, 10, 250, or 500 micrograms), an inhibitor of nitric oxide synthase, were examined in conscious rats following either osmotic stimulation (1.0 M NaCl, 15 ml/kg, s.c.) or induction of hemorrhage (0.7 ml/min to a 20% blood volume loss). Water intake increased in all animals. L-NAME at doses of 250 and 500 micrograms, but not 10 micrograms, significantly attenuated water consumption induced by both stimuli. The mean arterial blood pressure (MABP), which increased after osmotic stimulation, was maintained at pressor levels by 250 and 500 micrograms of L-NAME, but decreased progressively and reached basal levels after treatment with aCSF and the lowest dose of L-NAME (i.e., 10 micrograms). Hemorrhage significantly decreased MABP in all rats. The fall in blood pressure associated with hemorrhage returned to control levels in animals treated with 250 and 500 micrograms of L-NAME but not in those treated with aCSF or 10 micrograms of L-NAME. These results indicate that nitric oxide is involved in the regulation of drinking behavior and may play an important role in the central control of blood pressure during osmotic stimulation and hypotensive hemorrhage.     

Effects of nitric oxide synthase inhibition on brain infarction in SOD-1-transgenic mice following transient focal cerebral ischemia

To investigate the role of superoxide in the toxicity of nitric oxide (NO), we examined the effect of nitric oxide synthase (NOS) inhibition on brain infarction in transgenic mice overexpressing CuZn-superoxide dismutase (SOD-1). Male SOD-transgenic mice and non-transgenic littermates (30-35 g) were subjected to 60 min of middle cerebral artery occlusion followed by 24 h of reperfusion. Either NG-nitro-L-arginine methyl ester (L-NAME; 3 mg/kg), a mixed neuronal and endothelial NOS inhibitor, or 7-nitroindazole (7-NI; 25 mg/kg), a selective neuronal NOS inhibitor, was administered intraperitoneally 5 min after the onset of ischemia. At 24 h of reperfusion, the mice were decapitated and the infarct volume was evaluated in each group. In the nontransgenic mice, L-NAME significantly increased the infarct volume as compared with the vehicle, while 7-NI significantly decreased it. In the SOD-transgenic mice, L-NAME-treated animals showed a significantly larger infarct volume than vehicle-treated ones, whereas there were no significant differences between 7-NI- and vehicle-treated mice. Our findings suggest that selective inhibition of neuronal NOS ameliorates ischemic brain injury and that both neuronal and endothelial NOS inhibition may result in the deterioration of ischemic injury due to vasoconstriction of the brain. Since L-NAME increased infarct volume even in SOD-transgenic mice, the protective effect of SOD could result from the vasodilation by increased endothelial NO as well as the reduction of neuronal injury due to less production of peroxynitrite compared to wild-type mice. Moreover, the neurotoxic role of NO might not be dependent on NO itself, but the reaction with superoxide to form peroxynitrite, because of no additive effects of SOD and a neuronal NOS inhibitor.     

Role of laparoscopy in the management of chronic pelvic pain

OBJECTIVE: The pharmacokinetics of N(G)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) synthesis, was investigated in patients with septic shock. METHODS: Blood was sampled at intervals before, during and after 12-h infusion of L-NAME 1 mg x kg(-1) x h(-1) in nine septic shock patients for determination of plasma concentrations by high-performance liquid chromatography (HPLC). In three patients the renal clearance of the drug was determined. RESULTS: Incubation of L-NAME with plasma and blood in vitro revealed hydrolysis to N(G)-nitro-L-arginine (L-NOARG), the active inhibitor of NO synthesis. L-NOARG did not undergo further degradation. Continuous intravenous infusion of 1 mg x kg(-1) x h(-1) of L-NAME for 12 h in patients with septic shock increased blood pressure and resulted in increasing plasma concentrations of L-NOARG (Cmax 6.2 microg x ml(-1) at 12 h) whereas L-NAME concentrations reached a plateau within 1.5 h (Cmax 1.0 microg x ml(-1)). After the infusion was stopped L-NAME disappeared from the plasma rapidly (half-life 19.2 min) whereas L-NOARG concentration declined slowly (half-life 22.9 h). The calculated volume of distribution for L-NAME was 0.451 x kg(-1) body weight and 1.961 x kg(-1) for L-NOARG. The renal clearance for L-NOARG was 3.5% of total body clearance for L-NOARG, whereas L-NAME could not be detected in urine. CONCLUSION: We conclude that vasoconstriction with L-NAME in septic patients may result from hydrolysis to L-NOARG, the active inhibitor of NO synthesis. The long plasma half-life and large volume of distribution for L-NOARG suggests extensive distribution to extravascular tissues. Since renal excretion is minimal, elimination of the metabolite L-NOARG follows other pathways.     

Evidence that nitric oxide synthase is involved in progesterone-induced acrosomal exocytosis in mouse spermatozoa

In a recent work, we detected nitric oxide synthase (NO synthase) in the acrosome and tail of mouse and human spermatozoa by an immunofluorescence technique. Also, NO-synthase inhibitors added during sperm capacitation in vitro reduced the percentage of oocytes fertilized in vitro, suggesting a role for NO synthase in sperm function. Therefore, in the present study the effect of three NO-synthase inhibitors, NG-nitro-L-arginine methyl ester (L-NAME), NG-nitro-D-arginine methyl ester (D-NAME) and L-NG-nitro-arginine (NO2-arg), and of a nitric oxide donor, spermine-NONOate, on the progesterone-induced acrosome reaction of mouse sperm was examined. NO-synthase inhibitors were added at 0, 60 or 90 min during capacitation; at 120 min, mouse epididymal spermatozoa were exposed to 15 microM progesterone for another 15 min. In another set of experiments, different concentrations of spermine-NONOate were added to capacitated spermatozoa for 15 min; in these experiments, progesterone was not included. NO2-arg and L-NAME blocked progesterone-induced exocytosis regardless of the time at which these inhibitors were added. Moreover, D-NAME did not inhibit exocytosis. In contrast, spermine-NONOate stimulated the acrosomal exocytosis in vitro directly. These results provide evidence that mouse sperm NO synthase participates in the progesterone-induced acrosome reaction in vitro and that nitric oxide induces this event.     

Forearm nitric oxide balance, vascular relaxation, and glucose metabolism in NIDDM patients

Endothelium-dependent and -independent vascular responses were assessed in 10 NIDDM patients and 6 normal subjects with no evidence of atherosclerotic disease. Changes in forearm blood flow and arteriovenous (AV) serum nitrite/nitrate (NO2-/NO3-) concentrations were measured in response to intra-arterial infusion of acetylcholine (ACh) (7.5, 15, 30 microg/min, endothelium-dependent response) and sodium nitroprusside (SNP) (0.3, 3, 10 microg/min, endothelium-independent response). Insulin sensitivity (determined by minimal model intravenous glucose tolerance test) was lower in NIDDM patients (0.82 +/- 0.20 vs. 2.97 +/- 0.29 10(4) min x microU(-1) x ml(-1); P < 0.01). Baseline forearm blood flow (4.8 +/- 0.3 vs. 4.4 +/- 0.3 ml x 100 ml(-1) tissue x min(-1); NS), mean blood pressure (100 +/- 4 vs. 92 +/- 4 mmHg; NS), and vascular resistance (21 +/- 1 vs. 21 +/- 1 units; NS), as well as their increments during ACh and SNP, infusion were similar in both groups. No difference existed in baseline NO2-/NO3- concentrations (4.09 +/- 0.33 [NIDDM patients] vs. 5.00 +/- 0.48 micromol/l [control subjects]; NS), their forearm net balance (0.31 +/- 0.08 [NIDDM patients] vs. 0.26 +/- 0.08 micromol/l x 100 ml(-1) tissue x min(-1); NS), and baseline forearm glucose uptake. During ACh infusion, both NO2- and NO3- concentrations and net balance significantly increased in both groups, whereas glucose uptake increased only in control subjects. When data from NIDDM and control groups were pooled together, a correlation was found between the forearm AV NO2- and NO3- differences and blood flow (r = 0.494, P = 0.024). On the contrary, no correlation was evident between NO2- and NO3- concentrations or net balance and insulin sensitivity. In summary, 1) no difference existed in basal and ACh-stimulated NO generation and endothelium-dependent relaxation between uncomplicated NIDDM patients and control subjects; 2) in both NIDDM and control groups, forearm NO2- and NO3- net balance following ACh stimulation was related to changes in the forearm blood flow; and 3) ACh-induced increase in forearm blood flow was associated with an increase in glucose uptake only in control subjects but not in NIDDM patients. In conclusion, our results argue against a role of impaired NO generation and blood flow regulation in determining the insulin resistance of uncomplicated NIDDM patients; rather, it supports an independent insulin regulation of hemodynamic and metabolic effects.     

Tumor necrosis factor-alpha induces emphysema-like pulmonary tissue rebuilding. Changes in type II alveolar epithelial cells

This study has investigated the relative involvement of cholinergic, adrenergic, nitric oxide and tachykininergic transmission in extrinsic neural influences on the lower oesophageal sphincter (LOS) in urethane anaesthetized ferrets. A micromanometric assembly (OD 1.75 mm) incorporating a sleeve sensor was used for high-fidelity oesophageal, LOS and gastric pressure measurement at low perfusion rates (< 0.1 ml/min). The LOS response to vagal and splanchnic nerve stimulation (0.5 ms pulse width, 10 s duration) was frequency- and voltage-dependent. LOS responses to stimulation at 20 V, 10 Hz were investigated in separate groups of animals with either L-NAME (100 mg/kg), hexamethonium (15 mg/kg), guanethidine (5 mg/kg), CP96,345 (NK-1 antagonist, 4 mg/kg), atropine (0.4 mg/kg) or propranolol (1 mg/kg). Propranolol treatment was followed by yohimbine (1 mg/kg) and prazosin (0.25 mg/kg). Vagal stimulation caused an immediate decrease in LOS pressure, followed by increase on cessation of stimulation, followed by a prolonged decrease (77 +/- 2%) for up to 5 min. L-NAME did not affect inhibition, but increased excitation 4-fold (p < 0.001). Guanethidine and CP96,345 had no major effect. Hexamethonium decreased the inhibitory (p < 0.05) and excitatory (p < 0.01) responses. Atropine reduced the excitatory response (p < 0.05). Some inhibition still remained if all treatments were combined. Splanchnic stimulation reduced LOS pressure by 70 +/- 6% for 101 +/- 17 s. L-NAME, guanethidine, hexamethonium and CP96,345 all independently significantly reduced inhibition. The combination of guanethidine and CP96,345 usually abolished splanchnic-induced inhibition. Atropine was without effect. Propranolol (1 mg/kg) changed the splanchnic-induced response from mainly inhibition to excitation (100 +/- 44% increase). LOS responses to noradrenaline (1-10 micrograms close IA) showed similar features to responses to splanchnic stimulation. We conclude that vagal stimulation evokes LOS relaxation via activation of established cholinergic and NANC mechanisms and other, unidentified mechanisms. Splanchnic stimulation activates adrenergic neurones probably via nicotinic and non-nicotinic ganglionic mechanisms, which in turn elicit beta adrenergic inhibitory effects on the LOS. Splanchnic stimulation also antidromically activates spinal afferent fibres. These may release substance P from peripheral myenteric plexus and prevertebral ganglionic endings causing activation of myenteric NANC inhibitory neurones and sympathetic neurones, respectively.     

Effects of the ribavirin-interferon alpha combination on cultured peripheral blood mononuclear cells from chronic hepatitis C patients

The mechanisms associated with dysfunction of the cerebral vasculature following head trauma have not yet been fully elucidated. In an attempt to shed more light on the matter, we investigated the endothelial-mediated dilations in the rat middle cerebral artery (MCA) following severe traumatic brain injury (TBI). Rats were subjected to severe controlled cortical impact injury (CCI; 5 m/s, 130 ms duration, 3 mm deformation) over the right parietal cortex. At 24 h postinjury, ipsilateral segments of MCA and corresponding contralateral segments were isolated, mounted in a vessel chamber, and pressurized. The responses to 2 methylthio-ATP (2MeSATP), a selective agonist for the P2Y1 purinoceptors, N(omega)-nitro-L-arginine (L-NAME), an NO synthase inhibitor, and S-nitroso-N-acetylpenicillamine (SNAP), an exogenous NO donor, were determined. 2MeSATP elicited concentration dependent dilations in all MCAs studied. Ipsilateral MCAs harvested following TBI or sham-TBI, showed similar maximum dilations to 2MeSATP [70 +/- 4% (n = 17) and 72 +/- 6% (n = 13), respectively]. However, TBI reduced the concentration of 2MeSATP necessary to elicit one-half of the maximum dilation (EC50) from 15 to 9 nM (p < 0.05). Inhibition of NO synthase with 10(-5) M L-NAME abolished the dilation to 2MeSATP in both TBI and sham-TBI MCAs. The constriction to L-NAME was significantly reduced in TBI MCAs compared to sham vessels. Dilations to SNAP, an NO donor, were not altered by TBI indicating that the mechanisms of dilation involving NO in the vascular smooth muscle were not affected. Unlike other pathological conditions which often diminish endothelial-mediated responses, severe TBI enhanced the sensitivity to 2MeSATP without altering the maximum response.     

Deletions in Xq28 in two boys with myotubular myopathy and abnormal genital development define a new contiguous gene syndrome in a 430 kb region

The influence of the nitric oxide synthase inhibitor N-nitro-L-arginine methyl ester (L-NAME) on the copulatory behavior of sexually experienced male Wistar rats was investigated. L-NAME was injected i.p. 10 min before the onset of a session using a dose of 30 mg/kg (L-NAME 30 group), or 60 mg/kg (L-NAME 60 group). The copulatory sessions were terminated after the third ejaculation in the control group or after 1500 s in the L-NAME 30 and L-NAME 60 groups. L-NAME administration reduced the number of rats that achieved ejaculation by 43% and 86% in the L-NAME 30 and 60 groups, respectively. In both experimental groups only a few intromissions and an increased number of mountings were observed. An increase in the number of ultrasonic vocalizations in the 50 kHz band, a dose-dependent effect, was observed. The level of sexual motivation evaluated by mount latency was not influenced by inhibition of NO synthesis.