Potentiation of purinergic neurotransmission in guinea pig urinary bladder by histamine

Patients suffering from the inflammatory condition of interstitial cystitis frequently exhibit an increased number of mast cells in the bladder. To determine whether mast cell mediators have the potential to influence the neurogenic contraction of the bladder smooth muscle and thereby possibly contribute to the symptoms of interstitial cystitis, we examined the effects of histamine, a major inflammatory mediator of mast cell origin, on nerve- and agonist-induced contractions of in vitro strips of guinea pig urinary bladder. Histamine (10 microM.) potentiated by more than 50% the nerve-induced contraction of bladder strips evoked by field stimulation with 0.5 msec. pulses at 4 Hz. Because the neurogenic contraction of the bladder is mediated by at least two neurotransmitters, acetylcholine (ACh) and ATP, we examined the effects of histamine on each of these transmitters. Histamine potentiated responses to the purinergic component of the neurogenic response (that part of the neurogenic response that remains after treatment with atropine) and potentiated responses to exogenously applied ATP. Histamine did not potentiate the response to the cholinergic component of the neurogenic response (that part of the neurogenic response that remains after desensitization of purinoceptors with alpha, beta-methylene ATP) nor responses to carbachol, a cholinergic agonist. These results indicate that histamine potentiates the neurogenic response of the bladder by influencing the purinergic component, apparently at postjunctional sites.     

Effects of subchronic administration of metrifonate on cholinergic neurotransmission in rats

The effects of subchronic oral administration of metrifonate, a long-acting cholinesterase (ChE) inhibitor, on cholinergic neurotransmission were assessed in young adult male Wistar rats. Animals were treated twice daily with metrifonate. In a pilot study testing a 100 mg/kg dose of metrifonate for up to 14 days, ChE activity was found to steadily decrease to reach maximum inhibition levels of about 55%, 80% and 35% in brain, erythrocytes and plasma. Steady-state inhibition levels were attained by the 10th day of treatment. When metrifonate-treatment was discontinued, ChE activity in plasma returned to control levels within another day, while erythrocyte and brain ChE activity took more than 2 weeks to recover. In subsequent dose-response studies, metrifonate treatment was given for 3 and 4.5 weeks at doses of 0, 12.5, 25, 50, and 100 mg/kg, to different groups of animals, respectively. Correlation analysis indicted that brain ChE inhibition was more accurately reflected by erythrocyte than by plasma ChE inhibition, although all effects were highly correlated. The changes in ChE activity were not paralleled by changes in other parameters of the cholinergic neurotransmission, such as acetylcholine synthesis rate or acetylcholine receptor binding. It is therefore concluded that repeated administration of metrifonate to rats induces a long-lasting inhibition of ChE activity in a dose-related and predictable manner, which is neither subject to desensitization nor paralleled by counterregulatory downregulation of muscarinic or nicotinic receptor binding sites in brain.     

Neurotensin modulates cholinergic and noncholinergic neurotransmission in guinea-pig main bronchi in vitro

Guinea-pig main bronchi were stimulated transmurally in vitro by electrical field stimulation in the presence of indomethacin 10(-6) M, propranolol 10(-6) M and phosphoramidon 10(-5) M. Two contractile neurogenic responses were successively observed. The second noncholinergic contraction was concentration dependently inhibited or abolished by neurotensin whereas the first cholinergic contraction was only partially inhibited. SR 48692, a novel antagonist of neurotensin receptors, reduced the inhibition induced by neurotensin (pKB = 9.75) whereas levocabastine, an antagonist of low-affinity neurotensin receptors, did not significantly modify the inhibitory effects of neurotensin on both neurally-mediated contractions. These results demonstrate that neurotensin exerts an inhibitory effect on neurotransmission in guinea-pig airways. Furthermore, the present study shows that the newly developed neurotensin receptors antagonist, SR 48692, is a potent inhibitor of the neurotensin inhibitory effects on cholinergic and noncholinergic contractions induced by electrical field stimulation of the guinea-pig isolated main bronchus.     

Structure and function of the rabbit bladder altered by chronic obstruction or cystitis

In a prospective 5-year-study the development of adiposity was tested in a population group consisting of about 30,000 persons. It was shown that during the time of investigation the population decreased in its total number, the consumption of easily digestible carbohydrates and meat, however, increased. As it was established in 1968, the proportion of the adipose persons (more than 20% of the Broca-weight) and the percental average deviation from the Broca-weight (calculated in decennium classes) was more than in the comparable population groups in the GDR. Contrary to expectation the examination further showed that on an average men exhibited a trend to the increase in weight, but on the average women decreased in weight. In all age groups (with the exception of the 60- to 69-year-old persons) the proportion of obese persons was significantly lower in 1973 than in 1968. Unchangedly adipose are the diabetics who also have a by far higher average weight than the healthy population and who up to now do not reveal an inclination to the decrease in weight. With 2.9% the average frequency of diabetes is also adequately high.     

Clinical and pathologic characteristics of bladder squamous carcinoma

From 1973 to 1991, 782 patients with bladder tumor were admitted to this hospital. 23 (2.9%) of them were pathologically confirmed as squamous carcinoma. Clinically, 20 patients showed hematuria, 3 irritation signs of bladder, and 13 both signs. In this group, 82% the tumors belonged to B to D stage and 61% were of grade II. Six of 17 patients showed diffused eosinophil cell infiltration, suggesting a close relationship between bladder squamous carcinoma and inflammation. Bladder polycentric biopsy and exfoliative cytologic urocrisia were emphasized in preoperative diagnosis.     

The adrenergic, cholinergic and NANC nerve-mediated contractions of the female rabbit bladder neck and proximal, medial and distal urethra

1. The nerve-mediated contraction of the female rabbit bladder neck and different portions of the urethra (proximal, medial and distal) was studied in vitro by electrical stimulation (50 V, 30 Hz, 0.05 ms width, trains of 5 s every 5 min) by use of a superfusion system. 2. The amplitude (Emax) and the duration (Dmax) of the stimulated contraction were studied in the four tissues. The Emax value was significantly higher in distal urethra (2.07+/-0.15 g) compared to the bladder neck (1.08+/-0.10 g), proximal urethra (0.73+/-0.07 g) and medial urethra (0.87+/-0.07 g). In contrast, the Dmax value appeared slightly but significantly lower (P<0.05) in distal urethra (68.5+/-2.3 s) than in bladder neck (76.7+/-6.0 s), proximal urethra (84.5+/-5.0 s) and medial urethra (81.3+/-3.5 s). 3. Cocaine (1 microM) significantly increased the basal Emax values in medial and distal urethra and the basal Dmax values in the four tissues. 4. Prazosin (1 microM) significantly reduced E max value in proximal, medial and distal urethra and Dmax value in bladder neck and proximal urethra. Atropine (1 microM) also significantly reduced Emax values in bladder neck and proximal urethra and reduced Dmax value in bladder neck, but not in other tissues. Yohimbine (0.1 microM) was devoid of effect in the four tissues. 5. The association of prazosin (1 microM) and atropine (1 microM) did not modify the Emax and the Dmax values of the electrically-induced contractions, except in proximal urethra and in bladder neck where an additive inhibitory effect (on Emax only) was observed compared to prazosin and atropine alone. 6. The residual contractile response after combined treatment with prazosin and atropine was significantly diminished by tetrodotoxin (TTX; 1 microM) but not completely abolished. These NANC contractions were insensitive to P2X-purinoceptor desensitization by continuous tissue perfusion with alpha,beta-methylene ATP (30 microM). 7. These results demonstrate that bladder neck and proximal urethra are mainly innervated by the parasympathetic nervous system, whereas medial and distal urethras are to a greater extent under the control of the sympathetic innervation. The residual responses, insensitive to prazosin and atropine, may indicate a NANC innervation in the four tissues. However, the nature of the NANC neurotransmitter remains to be identified.     

Changes in cholinergic responses of sweat glands during denervation and reinnervation

Functional sudomotor responses have been studied in sweat glands reinnervated after sciatic nerve crush and partially denervated by cisplatin intoxication in the mouse. The sudomotor function mediated by the sciatic nerve was evaluated by silicone imprints on the plantar surface of the hindpaws. Five days after nerve crush, completely denervated sweat glands became unresponsive to cholinergic stimulation with pilocarpine. During the following weeks, the number of reinnervated, reactive sweat glands increased progressively to reach a maximum of 89% of preoperative control counts by 40 days after nerve crush. At this time, the mean volume of sweat secreted per gland was normal, but reinnervated glands showed a secretory activity abnormally sustained over time after pilocarpine stimulation and, on the other hand, had an increased resistance to the inhibition of secretion induced by atropine. The effects of cisplatin administration on sudomotor function were investigated in two groups of mice, one treated with high doses of cisplatin (10 mg/kg/week for 4 weeks) and another treated with low doses of cisplatin (5 mg/kg/week for 8 weeks). Cisplatin intoxication produced abnormal sudomotor responses indicative of denervation from cumulative doses of 10 mg/kg. The first abnormality found was a partial resistance of sweat glands to atropine, followed by a decrease in the sweat output per gland and finally a decline in the number of sweat glands activated by pilocarpine. These abnormalities in the sudomotor responses were more pronounced in mice treated with a high dose than in those with a lower dose regime.     

The neurogenic bladder in spinal cord injury--pattern and management

This study describes the various types of neurogenic bladder in spinal cord injury in relation to the level of lesion, defines the aims of bladder management, and discusses the importance of highly individualised management strategies and long-term follow-up. Urodynamic studies were done on 47 new patients with traumatic spinal cord injury when they had return of reflexic bladder activity. This study was conducted over a one-year period. Fifty-five per cent (n = 26) sustained cervical injuries (38.5% complete, 61.5% incomplete), 12.8% (n = 6) had thoracic injuries, 29.8% (n = 14) had lumbar injuries, and 2.1% (n = 1) had sacral injury. The urodynamic patterns according to injury level are shown in Table I. In patients with complete cervical injuries, 80% had detrusor sphincter dyssynergia (DSD), and areflexia was seen in 20% (n = 2). Of those with incomplete cervical injury, 7 (43.8%) had DSD, 5 (31.3%) had detrusor hyperrflexia without DSD, and 2 (12.5%) had areflexia or hyporeflexia. Normal urodynamic studies were only found in patients with incomplete cervical injury (n = 2). Of the 6 patients with thoracic injury, 4 (66.6%) had detrusor areflexia and 2 had DSD. The 2 patients with DSD had injury levels at T4/T6 and T5 respectively. Eleven (78.6%) patients with lumbar injury had detrusor areflexia, one (7.1%) had detrusor hyperreflexia (without DSD), and 2 (14.3%) had a normal urodynamic study. The various patterns of bladder management are shown in Table II. In total, there were 17 patients with DSD. Of these, 9 (52.9%) elected for intermittent catheterisation together with pharmacological therapy, 5 (29.4%) passed urine via spontaneous voiding/tapping, one (5.9%) had an in-dwelling catheter by virtue of his lack of manual dexterity and no care-giver, and 2 (11.8%) patients opted for sacral anterior root stimulator (SARS) or the Brindley device. Of the 6 patients with detrusor hyperreflexia, 4 (66.7%) passed urine spontaneously and 2 (33.3%) patients choose intermittent catheterisation together with pharmacologic therapy. There were 20 patients with detrusor areflexia/hyporeflexia; 15 (75%) were on clean intermittent catheterisation, 4 (20%) voided via straining and 1 (5%) had a suprapubic catheter inserted. The re-discovery of intermittent self-catheterisation, improved medical care, bladder training and surgical advances have enabled the goals of bladder management to be realised; namely safe bladder pressures, low residual urine volume and the attainment of continence.     

Effect of L-glutamate on cholinergic neurotransmission in various brain regions and during the development of rats, when administered perinatally

Glutamate, as a monosodium salt (MSG) has neurotoxic effects on some brain regions when systemically given to young rats. Few studies have been conducted to establish the mechanisms involved in studying neurotoxicity resulting in neuronal death by glutamate (Glu) and its effects as related to different brain neuropathologies under in-vivo conditions and where the cholinergic system shows vulnerability. Thus, this paper aims to evaluate the binding kinetics of quinuclynidyl benzylate (QNB) to muscarinic receptors for acetylcholine and the activity of choline acetyltransferase (CAT) in rats treated with MSG (4 mg/g on days 1, 3, 5, and 7 after birth) during the rat development stages (days 14, 21, 30, and 60) in different brain regions. The results show that perinatal treatment with MSG significantly decreases the CAT activity and increases the affinity of [3H]-QNB and the number of receptors of the brain cortex during the ages studied. The striatum showed increased CAT activity and BMAX on days 30 and 60 after birth. Affinity and the number of receptors increased in the hippocampus only between days 21 through 60 after birth. NaCl given at MSG equimolar doses only modified the CAT activity but had no effect on the [3H]-QNB binding kinetics in any of the regions studied. The results show that MSG alters cholinergic neurotransmission in the central nervous system (CNS) and induces the development of compensating events suggesting an involvement in neuronal plasticity during the development of rat CNS.     

Nitrergic neurotransmission mediates the non-adrenergic non-cholinergic responses in the clitoral corpus cavernosum of the rabbit

The corpus cavernosum is the erectile tissue in the penis and clitoris. Although nitrergic neurotransmission has been characterized in detail in the penile corpus cavernosum, functional studies on the inhibitory non-adrenergic non-cholinergic (NANC) transmission in the clitoral corpus cavernosum have been lacking. Here we demonstrate that electrical field stimulation (EFS) induces NANC relaxation responses in the clitoral corpus cavernosum of the rabbit. These responses were inhibited by NG-nitro-L-arginine methylester (L-NAME), 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ) or tetrodotoxin. The inhibitory effect of L-NAME was partially reversed by L-arginine but not by D-arginine. EFS-induced relaxations were enhanced by an inhibitor of type V cyclic GMP phosphodiesterase, zaprinast. These results suggest that nitrergic neurotransmission is responsible for the NANC relaxation responses in the clitoral corpus cavernosum of the rabbit.     

Activation of dopaminergic and cholinergic neurotransmission by tachykinin NK3 receptor stimulation: an in vivo microdialysis approach in guinea pig

The regulation of dopaminergic and cholinergic function by neurokinin-3 (NK3) receptor activation was examined in vivo in urethane-anaesthetized guinea pigs with microdialysis probes. The local application of the NK3 tachykinin receptor agonist senktide in the region of dopamine cell bodies (pars compacta of the substantia nigra and ventral tegmental area) and in the area of cholinergic cell bodies (septal area) markedly enhanced the extracellular dopamine (DA) and acetylcholine (ACh) concentration throughout their respective target areas, i.e. striatum, nucleus accumbens, prefrontal cortex for dopaminergic systems and hippocampus for cholinergic neurons. The enhancing effect of senktide on neurotransmitter release was dose dependently blocked by the selective non-peptide NK3 receptor antagonist SR142801 (0.1-1 mg/kg, i.p.), whereas its inactive S-enantiomer SR142806 (0.3-1 mg/kg, i.p.) did not exert any antagonistic activity on the effect of intranigral or intraseptal application of senktide. These results demonstrate that NK3 receptors can modulate the activity of central DA and ACh systems.     

Cancer of the bladder in spinal cord injury patients

Since 1963, 10 cases of bladder carcinoma have been detected in 1,052 new admissions to our center. A high percentage of these patients had squamous cell carcinoma and/or squamous elements. This relatively high incidence stimulated a prospective study of 81 spinal cord injury patients either maintained on intraurethral catheter drainage for 10 years or an external appliance for 15 years. There were changes of squamous metaplasia in 19 per cent of the cases but no cancer was detected. It remains undetermined if squamous metaplasia is a pre-malignant lesion. However, the incidence of squamous metaplasia and squamous cell carcinoma in paraplegics with chronically infected bladders is not uncommon. Any spinal cord injury patient with hematuria needs a complete bladder evaluation and any long-term paraplegic with chronic infection should undergo cystoscopy and Papanicolaou smears as part of the yearly checkup.     

Changes in canine bladder perfusion with distension

Using a radioisotope-labeled microsphere technique, canine bladder perfusion was investigated. Blood flow was measured in in flaccid and distended conditions. A slight decrease in total bladder blood flow was recorded. There was a relative decrease in bladder mucosal flow with distension. There was no difference in perfusion of dome versus trigone.     

Changes in immunological potential between juvenile and presenile in rabbit

To investigate the relationship between immunological potential and advance of age, patterns of humoral immune response in different aged rabbits were compared. In the primary response, the appearance of total antibody and the arrival to its peak level were retarded by advance of age. On the other hand, the appearance of IgG antibody was the earliest in young and young adult rabbits though the arrival to its peak level was the latest. The disappearance of total and IgG antibodies was earlier in older and immature animals. In the secondary response, the reincrease of total antibody occurred on the same day regardless of the age, but the older were the rabbits, the earlier was the reincrease of IgG antibody and also the arrival to the peak level of both antibodies. In the primary and the secondary responses, the maximal titers of both antibodies were the highest in young and young adult groups. From these results, the exact comparison of immunological potentials in rabbits of different age is possible only by the comparison of patterns of immune responses together with their intensity.     

Effects of L-NG-nitro arginine on cholinergic transmission in the gastric muscle of the rabbit

In the circular muscle of the rabbit gastric corpus, the nitric oxide-synthesis inhibitor L-NG-nitro arginine (L-NOARG), enhanced the neurally-induced cholinergic responses evoked by electrical field stimulation (EFS) and ganglionic stimulating agents (nicotine, dimethylphenyl piperazinium iodide). The muscular contractions caused by acetylcholine (Ach) and methacholine were not influenced by the nitric oxide-synthesis inhibitor. The nitric oxide-releasing compound sodium nitroprusside (SNP) did not affect the Ach-induced muscular responses. Our results suggest that L-NOARG enhances gastric cholinergic responses by removing an inhibitory influence exerted at the prejunctional level in the nerve-muscle pathway.     

Nicotinic cholinergic influences in pancreatic secretion induced by intraduodenal alkaline and acid solutions in the rabbit

1. The effect of hexamethonium on the exocrine pancreatic response to intraduodenal acidification and alkalinization, and the secretin and VIP release after these stimuli, was studied. 2. The hydroelectrolyte secretion after hydrochloric acid and sodium carbonate perfusion was reduced by hexamethonium treated (322 +/- 44% of maximum response in flow rate to sodium carbonate perfusion in untreated animals vs 140 +/- 12% in pretreated animals, and 252 +/- 19% of maximum response in flow rate to HCl in untreated animals vs 166 +/- 11% in pretreated animals). 3. However, hexamethonium has no effect on secretin plasma levels after either intraduodenal acidification or alkalinization. 4. On the contrary, the ganglion blocker significantly (P < 0.01) reduced plasma VIP levels in response to intraduodenal HCl (maximum response 320 +/- 74% in untreated vs 184 +/- 44% in hexamethonium-treated animals). 5. Plasma VIP levels showed a similar increase in both untreated (maximum response: 151 +/- 12%) and ganglion blocked animals (170 +/- 26%) in response to sodium carbonate. 6. These data suggest the existence of complex neural mechanisms in the exocrine pancreatic response to intraduodenal stimuli, these mechanisms being different depending on the intraduodenal stimulus.     

Use of ultrasound in spinal arthrodesis. A rabbit model

STUDY DESIGN: The biomechanical and histologic characteristics of posterolateral spinal fusion in a rabbit model with and without the application of low-intensity ultrasound were analyzed. OBJECTIVES: To evaluate the use of ultrasound to improve the spinal fusion rate and biomechanical characteristics of the fusion mass in a rabbit model. SUMMARY OF BACKGROUND DATA: This is the first study in which the benefits of ultrasound in spinal fusion have been assessed. Posterolateral intertransverse process fusion in the rabbit has a pseudarthrosis rate similar to that recorded in humans (5-40%). METHODS: Fourteen New Zealand White rabbits were randomly assigned to each of two groups to undergo spinal fusion using autologous bone with ultrasound or autologous bone without ultrasound. A specially designed plastic constraint was used to focus the ultrasound over the rabbits' lumbar spine 20 minutes per day. Animals were killed at 6 weeks for biomechanical and histologic testing. RESULTS: The rate of pseudarthrosis, evaluated radiographically and manually in a blinded fashion, decreased at a statistically significant rate (from 35% to 7%) with ultrasound. Biomechanical analysis of the fusion mass showed that ultrasound resulted in statistically significant increases in stiffness (33%; P = 0.03), area under the load displacement curve (25%; P = 0.05), and load to failure of the fusion mass (24%; P = 0.04). Qualitative histologic assessment showed increased bone formation in those fusions exposed to ultrasound. CONCLUSIONS: Lumbar spinal fusion is a complex biologic process. The results of the current study demonstrate the reproducibility of a rabbit fusion model and the ability of ultrasound to induce a statistically significant increase in fusion rate, stiffness, area under the load displacement curve, and load to failure of the fusion mass. These results provide a basis for continued evaluation of biologic improvement of spinal arthrodesis with the use of ultrasound.     

Identification and characterization of a high-affinity peripheral-type benzodiazepine receptor in rabbit urinary bladder

The present study used radioligand binding and in vitro contractility experiments to identify and characterize a peripheral-type benzodiazepine receptor PBR in rabbit urinary bladder. [3H]PK11195 bound to bladder membranes with high-affinity and density (Kd = 5.2 nM., Bmax = 268 fmol./mg. protein), indicating the presence of a PBR. [3H]flunitrazepam bound with high-affinity and density (Kd = 1.2 nM., Bmax = 48 fmol./mg. protein). The rank order potency of various benzodiazepines and isoquinoline carboxamides in displacing the binding of [3H]PK11195 was Ro5-4864 > diazepam = flunitrazepam > Ro15-1788 = clonazepam. Ro5-4864 and PK11195 inhibited nerve-evoked contractions in a concentration-dependent manner (IC50 = 42 microM. and 56 microM., respectively). Carbachol- and KCl-induced contractions were also inhibited by Ro5-4864 and PK11195. KCl-induced contractions were inhibited to a greater extent than carbachol-induced or field-stimulated contractions with all the drugs tested. Both Ro5-4864 and PK11195 significantly increased the ED50 for calcium-induced contractions following a cholinergic stimulus compared with control. These data demonstrate the presence of a PBR in urinary bladder capable of altering contractility in vitro through modulation of calcium activity.     

Experimental induction of maligant tumors in the urinary bladder of the rabbit

Suspended material of Brown-Pearce carcinoma is qualified for producing bladder tumors in rabbits after injection into the wall of the exposed, but not opened bladder. The advantages are the rapid growing and the possibility of controlling by endoscopy and radiography. At present we use this tumor-pattern for examination of the effect of different laser beams in experimental bladder tumors.