The smooth-muscle adrenoreceptors of rat and guinea pig tracheas

Effects of adrenaline and noradrenaline upon the smooth muscle contractile activity were shown to have a biphasic character. In low concentrations the effects coincide with that of phenylephrine, in high concentrations--with that of isadrine. The alpha-adrenoreceptors seem to be located at the metasympathetic neurons of the intramural ganglia and at postganglionic cholinergic nervous fibers, whereas the beta-adrenoreceptors at the smooth muscle cells.     

Immunological reactivity of the lung. I. A guinea pig model for the study of pulmonary mononuclear cell subpopulations

The effects of various regimens of cyclophosphamide administration on guinea pig peripheral blood leukocytes were studied. Cyclophosphamide-induced immunosuppression was assessed by the effect of drug administration on the proportions and absolute numbers of leukocyte populations, and by the effect on functional capabilities of unfractionated and adherent cell-depleted mononuclear cell suspensions as measured by the PHA-induced cellular cytotoxicity and antibody-dependent cellular cytotoxicity assays against chicken erythrocyte targets. Intraperitoneal administration of five daily doses of cyclophosphamide (5 mg/kg) caused a modest absolute leukopenia but no change in cytotoxic effector function of the mononuclear cells remaining in the circulation. As the dosage of cyclophosphamide was increased to 20 mg/kg/day to produce a pronounced leukopenia, a profound neutropenia (less than 300 polymorphonuclear leukocytes/mm3) together with a marked decrease in mononuclear cell effector function was noted. A single i.p. injection of cyclophosphamide (100 mg/kg), which produced identical degrees of leukopenia of each leukocyte class as did daily administration of cyclophosphamide (20 mg/kg/day), caused no change in mononuclear cell effector function when compared to saline controls. Complement receptor-bearing and Fc-receptor bearing mononuclear cells were decreased to the same degree by both regimens of cyclophosphamide administration. Removal of adherent cells from mononuclear cell suspensions by column purification resulted in a marked decrease in cytotoxic effector function at low effector to target ratios. At higher effector to target ratios there was no difference in cytotoxic effector function between unfractionated and column-purified cells. In contrast, the functional defect in mononuclear cell suspensions from animals that received five daily doses of cyclophosphamide (20 mg/kg) could not be compensated for at higher effector to target ratios, indicating that this functional defect was not an artifact of relative depletion of monocytes by cyclophosphamide, but was due to an actual suppression of the effector functional capabilities of the killer cells. This study indicates that, dependent on the particular regimen of drug administration, the quantitative depletion of mononuclear cell populations by cyclophosphamide administration can be clearly distinguished from the qualitative effect on certain functional capabilities of surviving cells.     

Nitric oxide synthase inhibitor and lipopolysaccharide effects on reactivity of guinea pig airways

The in vivo and in vitro effects of nitric oxide (NO) synthase inhibitors and lipopolysaccharide (LPS) on reactivity of guinea pig airways were examined. In isolated, perfused tracheas from untreated animals, the NO synthase inhibitors, N omega-nitro-L-arginine methyl ester (L-NAME; 10(-4)M), NG-methyl-L-arginine (L-NMMA; 10(-4) M) and aminoguanidine (10(-4) M) had no effect or inhibited reactivity to extraluminally (EL) or intraluminally (IL) applied methacholine and histamine. L-NMMA (10(-4) M) did not appreciably contract resting or metacholine-contracted preparations (+/- 3 x 10(-4) M L-arginine) and L-arginine only weakly relaxed contracted tracheas (+/- L-NMMA). Sodium nitroprusside and S-nitroso-N-penicillamine elicited relaxant responses and were more potent extraluminally than intraluminally. Methylene blue (10(-5) M) antagonized relaxation to sodium nitroprusside. Incubation with Escherichia coli LPS (10 micrograms/ml; 30 min incubation) alone in the EL and IL baths depressed methacholine and histamine concentration-response curves. In the presence of LPS, L-NAME potentiated responses to intraluminally applied methacholine but did not affect responses to extraluminally added methacholine. Four days after i.p. injection of animals with LPS (4 mg/kg), L-NAME potentiated responses to IL methacholine, and L-arginine acquired greater relaxant activity. LPS injection increased sensitivity to intraluminally added but not extraluminally added isoproterenol. LPS given by i.p. injection or by inhalation did not affect basal specific airway resistance of conscious animals or reactivity to methacholine aerosol during a postexposure period of 6 to 72 h. NO seems to have little role in regulating reactivity of guinea pig airways to bronchoconstrictor agonists, except after in vitro or in vivo exposure to LPS. After LPS injection the in vitro changes suggestive of NO synthase induction are not associated with altered airway reactivity to inhaled methacholine.     

A quantitative study of articular repair in the guinea pig

This study examined the healing of articular defects, with and without carbon fiber implants, and the response of repair tissue to its interim removal in guinea pigs of different ages. These were investigated after the induction of full thickness articular cartilage defects in the patellar groove of skeletally mature and immature guinea pigs. To indicate its capacity for replacement after attrition, repair tissue occurring in untreated (control) and carbon fiber treated (experimental) defects was ablated after 8 weeks, and the animals were sacrificed after an additional 8 weeks. The repair tissue was studied quantitatively at gross and microscopic levels and qualitatively using scanning and transmission electron microscopic study. The principal findings were as follows. The initial formation of repair tissue was variable, but it occurred in most cases. Secondary repair tissue formation consistently occurred after excision. Age did not influence the degree of repair. Carbon fiber implants of the type used impaired healing of small full thickness articular cartilage defects, compared with no treatment. Microscopically, repair tissue contains five main cell types, each with a characteristic surrounding matrix. Intermediate forms also are found. These, together with four of the five main types comprise a morphologic continuum and fit readily into a proposed developmental sequence that may stem from the fibroblast.     

A comparison of the beta-blocking activities of practolol, sotalol, and propranolol in human and guinea pig tracheal smooth muscle

Beta adrenergic blockade was studied in vitro with human tracheal muscle strips and guinea pig tracheal chains. It was shown in isolated smooth muscle from both man and guinea pig that the order of potency for the three beta-blocking agents studied was: propranolol greater than sotalol greater than practolol. Under the conditions of this study, propranolol was about 30,000 times and sotalol about 30 times as potent as practolol. The order of potency suggests that the nature of adrenergic blockade induced by practolol on tracheal smooth muscle is only weakly beta2-relative to the blocking effects of propranolol and sotalol. Beta adrenergic blockade by propranolol, sotalol, and practolol produced different degrees of increased histamine lethality in mice. Whereas both propranolol at 0.01 mg/kg and sotalol at 1.0 mg/kg resulted in 100% histamine-induced lethality, practolol at 50 mg/kg resulted in only 50% histamine-induced lethality. These data, when added to those from our previous studies, suggest that the mechanisms responsible for resistance to the effects of histamine in untreated mice are at least partially mediated by the beta2-adrenergic system. Thus, in three different tissues, the blocking activity of practolol was shown to be less than that of sotalol or propranolol.     

Paracrine endothelin signaling in the control of basal cell proliferation in guinea pig tracheal epithelium

Immunofluorescent analyses revealed distinct cellular/subcellular localization of endothelin (ET) receptors and ET-1 in the epithelial cell layer of guinea pig trachea. ETA was expressed predominantly in the basal cells. ETB was expressed predominantly in the ciliated columnar cells and was polarized at the apical side of the cell body within the cells. Anti-ET-1-immunoreactive cytoplasmic granules were contained in the secretory cells that were scattered throughout the epithelial layer. Cell proliferation assays with immersion cultures of differentially plated cells (basal cell-enriched, non-basal cell-enriched and mixed cell cultures) indicated the presence of paracrine ET-1 signaling pathways that transmit both positive and negative effects on the basal cell proliferation. Direct activation of ETA expressed on the basal cells caused enhancement of their growth, whereas that of ETB expressed on the ciliated columnar cells caused suppression of the basal cell growth. The latter effect was transmitted by nitric oxide whose production was stimulated by ETB activation. Furthermore, blockade of either ETA or ETB compromised the epithelial cell layer formation under the air-interphase culture, which indicates the dependence of tracheal epithelial remodeling on a balance between the positive and negative effects of ET-1 on the basal cell growth.     

Nonuniform biosynthesis of multiple hemoglobins in the adult rat and guinea pig

Separation of adult rat bone marrow cells by the method of thin layer countercurrent distribution permits the analyses of 59Fe-tagged erythroid cells for the various multiple hemoglobins and the assignment of such hemoglobins to erythroid cells at different stages of their development. Of the six adult red cell hemoglobins, hemoglobin 5 is synthesized most actively in the earliest erythroid cell whereas hemoglobin 4 (the major hemoglobin of the red cell) is synthesized most actively in the latest erythroid cells, e.g. the reticulocyte. Experimental evidence also indicates that maturation of the erythroid cell is accompanied by a decreased rate of synthesis of hemoglobin 5. The earliest erythroid cells of the marrow contain two hemoglobins, 7 and 8, which are absent in the adult red cell. Similar studies with the guinea pig confirm the nonuniform biosynthesis of its two hemoglobins and suggest that the phenomenon may be a general one among mammalian multiple hemoglobins.     

Comparative study of the effects of clozapine and clothiapine in different preparations of guinea pig and rat isolated organs

1. A study has been made to know the effects of clozapine and clothiapine on the responses of rat isolated vas deferens to norepinephrine, dopamine and potassium, those of the rat isolated uterus to serotonin and potassium, and that of guinea pig isolated ileum to histamine. 2. Clozapine was a noncompetitive antagonist to norepinephrine, dopamine, serotonin and histamine; it inhibited potassium-induced contraction in isolated rat uterus and vas deferens. 3. Clothiapine was a competitive antagonist to serotonin and a noncompetitive antagonist to norepinephrine, dopamine and histamine; it inhibited potassium-induced contractions in isolated rat uterus and vas deferens.     

Effect of short and long-term exposure to diesel exhaust on sensitivity of guinea pig tracheal preparation to histamine

Single exposure, to diesel exhaust (1 part exhaust diluted by 5 parts of clean air) reduced EC50 of histamine indicating hyperresponsiveness of the receptors in trachea of exposed guinea pigs. In contrast, following repeated exposure for 7, 14 or 21 days (15 min/day), EC50 was progressively increased indicating the possibility of down-regulated histamine receptors. Further, simultaneous significant increase in histamine levels (bioassayed on guinea pig ileum) in bronchial airway lavage fluid supports the aforementioned hypothesis. The change in lung/body weight ratio and suspended particulate matter deposited on filters followed the same temporal pattern as EC50. The findings are suggestive of differential effects of diesel exhaust on airway depending upon the duration of exposure.     

Ontogeny of spontaneous locomotor activity in rabbit, rat, and guinea pig.

Investigated postnatal locomotor activity in 3 experiments with 43 New Zealand white rabbits, 20 Sprague-Dawley albino rats, and 11 Dunkin-Hartley albino guinea pigs. A peak was found in this behavior at 5 days of age in the rabbit and, in confirmation of earlier studies, at 15-20 days in the rat. Neonatal guinea pigs showed no variation in activity levels due to age. The guinea pig is born at an advanced stage of neural maturation in comparison with the rat, and the rabbit is born at an intermediate stage. This difference accounts for the observed variations in postnatal activity profiles if it is assumed that the behavioral peak coincides with the transition from a stage of primarily mesencephalic arousal system maturation to a stage of primarily diencephalic and telencephalic inhibitory system maturation. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A model for tracheal study

While attempting to devise a valvular device to prevent aspiration in tracheo-esophageal anastomosis, we employed a model in the dog, which we feel would be very useful in the study of other tracheal problems. Essentially, a segment of trachea with its blood supply intact is isolated and turned through 90 degrees. One end of the segment is then anastomosed to the skin whereas the other end is either anastomosed to the gullet or covered with silastic, depending upon the required investigation. In both cases, after an interval of at least nine months, the segment continued to be lined by respiratory epithelium and no stenosis had occurred. Where silastic sheeting was employed to cover the end of the segment, the inner aspect of the silastic was covered with a thin layer of fibrous tissues lined by respiratory epithelium.     

Evidence that guanylate cyclase is involved in modulating the resting tension and neurally-induced contraction of the guinea pig tracheal muscle

Electrical field stimulation of guinea-pig tracheal muscle strips produced a frequency-dependent biphasic response consisting of an initial cholinergic contraction followed by relaxation. Both phases of the response were of neural origin. In the presence of methylene blue, a guanylate cyclase inhibitor, the resting tension and the contraction were increased, but the accompanying relaxation was inhibited. However, in the presence of sodium nitroprusside, a guanylate cyclase activator, the resting tension was reduced and the contraction was inhibited, but the relaxation was prolonged and increased. Similarly, in the presence of either 3-isobutyl-1-methylxanthine, which promotes cyclic guanosine monophosphate (cGMP) accumulation, or 8-bromo-cGMP, an analogue of cGMP, the resting tension was reduced and the contraction was inhibited but the relaxation was prolonged and increased. From these results, it is concluded that guanylate cyclase is involved in modulating the resting tension and the neurally-induced contraction of guinea-pig tracheal muscle.     

Sensory innervation of the digital, palmar and plantar pads of the rat and guinea pig

The Authors have studied, with Ruffini's gold-chloride method, the sensitive innervation of the digital, metacarpal and metatarsal pads of the rat and guinea-pig. Nervous capsulated expansions and free terminations are described in this district.     

Pathohistological study of adriamycin-induced tracheal agenesis in the fetal rat

Mr 2266 [(-)-(1R,5R,9R)-5,9-diethyl-2-(3-furylmethyl)-2'-hydroxy-6,7-benzomorpha n] is an antagonist at kappa-opioid receptors and at ORL1 receptors as well. The aim of our study was to examine whether the known stereoselective antagonism of Mr 2266 at kappa-opioid receptors also extends to ORL1 receptors. In mouse brain cortex membranes, the binding of the ORL1 receptor agonist [3H]nociceptin was equipotently inhibited by Mr 2266 and its enantiomer Mr 2267 (pK(i) 4.82 and 5.14, respectively), whereas the binding of the kappa-opioid receptor agonist [3H]U-69,593 was inhibited by Mr 2266 more potently (pK(i) 9.11) than by its enantiomer Mr 2267 (pK(i)7.15). In mouse brain cortex slices preincubated with [3H]noradrenaline, the concentration-response curve of nociceptin for inhibition of the electrically evoked overflow of tritium was equipotently shifted to the right by Mr 2266 and Mr 2267 (pA2 5.77 and 5.64, respectively). On the other hand, the inhibitory effect of U-69,593 on the electrically evoked overflow of tritium in guinea-pig brain cortex slices preincubated with [3H]noradrenaline was more potently antagonized by Mr 2266 (pA2 8.81) than by Mr 2267 (pA2 7.15). These data show that the stereoselective antagonism of Mr 2266 at kappa-opioid receptors does not extend to ORL1 receptors.     

A comparative study of transcranial Doppler sonography and near-infrared spectroscopy for the assessment of cerebrovascular CO2 reactivity

Oleanolic acid (1) was identified as an anti-HIV principle from several plants, including Rosa woodsii (leaves), Prosopis glandulosa (leaves and twigs), Phoradendron juniperinum (whole plant), Syzygium claviflorum (leaves), Hyptis capitata (whole plant), and Ternstromia gymnanthera (aerial part). It inhibited HIV-1 replication in acutely infected H9 cells with an EC50 value of 1.7 microg/mL, and inhibited H9 cell growth with an IC50 value of 21.8 microg/mL [therapeutic index (T. I.) 12.8]. Pomolic acid, isolated from R. woodsii and H. capitata, was also identified as an anti-HIV agent (EC50 1.4 microg/mL, T. I. 16.6). Although ursolic acid did show anti-HIV activity (EC50 2.0 microg/mL), it was slightly toxic (IC50 6.5 microg/mL, T. I. 3.3). A new triterpene (11) was also isolated from the CHCl3-soluble fraction of R. woodsii, though it showed no anti-HIV activity. The structure of 11 was determined to be 1beta-hydroxy-2-oxopomolic acid by spectral examination. Based on these results, we examined the anti-HIV activity of oleanolic acid- or pomolic acid-related triterpenes isolated from several plants. In addition, we previously demonstrated that derivatives of betulinic acid, isolated from the leaves of S. claviflorum as an anti-HIV principle, exhibited extremely potent anti-HIV activity. Accordingly, we prepared derivatives of oleanolic acid and evaluated their anti-HIV activity. Among the oleanolic acid derivatives, 18 demonstrated most potent anti-HIV activity, with an EC50 value of 0. 0005 microg/mL and a T. I. value of 22 400.     

Stereoselectivity of the aliphatic hydroxylation of 6-n-propylchromone-2-carboxylic acid in rat and guinea pig

Following administration of 6-n-propylchromone-2-carboxylic acid (6-n-PCCA) (500 mumol/kg) to male rats, three metabolic products were detected and isolated from the 0-24 h urine. All were identified as resulting from oxidation exclusively along the 6-n-propyl moiety. Some 66% of the dose was excreted in the 0-24 h urine, 55% of which was 6-PCCA, with 15% as (6-1'-hydroxypropyl)chromone-2-carboxylic acid (6-1'-HPCCA), 22% as 6-(2'-hydroxypropyl)chromone-2-carboxylic acid (6-2'-HPCCA), and 4% as 6-3'-carboxypropyl)chromone-2-carboxylic acid (6-3'-CPCCA). Derivatization of the methyl esters of the hydroxylated metabolites with S-alpha-methoxy-alpha-(trifuloromethyl)-phenylacetyl chloride (Mosher's reagent) allowed the evaluation of urinary enantiomeric composition by HPLC and assignment of their absolute configurations by NMR. This was found to be 90:10 (R/S) for 6-2'-HPCCA, and 7:93 (R/S) for 6-1'-HPCCA. When rats were dosed with the racemic 1'- and 2-hydroxy metabolites; no stereoselective metabolism or excretion was observed. Administration of 6-n-PCCA to male guinea pigs revealed that this species was unable to metabolise this compound.