Rat Stomach Strip Research Articles

ОПТИЧНА СИСТЕМА РЕЄСТРАЦІЇ СКОРОЧЕННЯ ГЛАДЕНЬКИХ М'ЯЗІВ В ІЗОМЕТРИЧНОМУ РЕЖИМІ

The optical system registration of smooth muscle contraction in isometric mode was developed. Testing of system on smooth muscle strips of rat stomach and caecum was performed. It was tested the possibility of recording optical system spontaneous activity of smooth muscle. The resulting muscle contractions parameters correspond to the literature. Thus designed optical-mechanical method for detecting force and speed can be used for recording isometric contractions of smooth muscles of the stomach and caecum of rats and, therefore, to study the effect of different effectors their mechanokinetic.

A novel bombesin-like peptide from skin of Rana shuchinae

Bombesin and its receptors have been demonstrated to be involved in a larger array of physiological and pathophysiological conditions including memory and fear behavior, lung development and injury, and tumor growth. A bombesin-like peptide named bombesin-RS was purified and characterized from the skin secretions of the frog, Rana shuchinae. Its amino acid sequence (pETSFMAPSWALGHLM-NH2) was determined by auto Edman degradation and mass spectrometry. The cDNA encoding bombesin-RS precursor was cloned from skin cDNA library of this frog. The precursor is composed of 67 amino acid residues including a copy of mature bombesin-RS. Two predicted enzymatic processing sites (-Lys-Lys- and -Lys-Arg-) are flanked at the mature bombesin-RS sequence. In the in vitro myotropic contraction experiment, the synthesized bombesin-RS displayed stimulating effect toward rat stomach strips, suggesting that bombesin-RS acts as agonist as most other bombesin-related peptides do.

Effects of methanolic root extract of ledebouria ovaltifolia (hyacithaneae) on isolated smooth muscle preparation in rats

This study investigated the receptor effects of methanolic root extract of ledebouria ovaltifolia on Acetylcholine and Potassium (K + ) induced contractions in Rat stomach strip (RSS), Adrenaline and K + (induce contractions) in rat vas deferens (RVD), and carbachol and K + induced contractions in rat uterus (RUT). Effects of the root extract (1.27mg/mL) on acetylcholine (6.8x10 -9 to 10.4x10 -8 M) adrenaline 2x10 -7 M, carbachol (2x10 8 M-1.6x10 -7 M), and K + contractions were non competitive. Results of muscle contractility in zero-Ca 2+ containing 0.5mM EGTA varies in these tissues in this order RSS>RVD>RUT. It is concluded in this study, the inhibitory effect of the extract was non specific on muscarinic, adreneceptors nor depolarised membrane site. The effect of the extract was more marked on potassium (K + ) than receptor mediated contractions.

A bombesin-like peptide from skin of Sanguirana varians

Bombesin-like peptides (BLPs) are a family of neuro-endocrinic peptides that mediates a variety of biological activities. A BLP named bombesin-SV from the skin secretions of the frog, Sanguirana varians, was purified and characterized. Its amino acid sequence is pEMIFGAPMWALGHLM-NH2 determined by Edman degradation and mass spectrometry. The cDNA encoding bombesin-SV precursor was cloned from skin cDNA library of S. varians. The precursor is composed of 67 amino acid residues including a copy of mature bombesin-SV. Two predicted enzymatic processing sites (-Lys-Arg-) are flanked at the mature bombesin-SV sequence. In the in vitro myotropic contraction experiment, the synthesized bombesin-SV displayed the stimulating effect toward rat stomach strips, suggesting that bombesin-SV acts as agonist as most other BLPs do.

Comparison of Smooth Muscle Contractility in Rat Vas Deferens (Tube) and Rat Stomach Strip (Sheet) in Various Physiological Salt Solutions

Comparison of Smooth Muscle Contractility in Rat Vas Deferens (Tube) and Rat Stomach Strip (Sheet) in Various Physiological Salt Solutions

Studies on Antagonistic Action of Methanolic Extract of Ledebouria ovaltifolia on Isolated Rat Stomach Strip and Rabbit Jejenum Preparations

Studies on Antagonistic Action of Methanolic Extract of Ledebouria ovaltifolia on Isolated Rat Stomach Strip and Rabbit Jejenum Preparations

Multiple bombesin-like peptides with opposite functions from skin of Odorrana grahami

Bombesin-like peptides (BLPs) are a family of neuroendocrinic peptides that mediate a variety of biological activities. Three mature BLPs from the skin secretions of the frog Odorrana grahami were purified. Several bombesin-like peptide cDNA sequences encoding precursors of BLPs were identified from the skin cDNA library of O. grahami. This is the maximal diversity of BLPs ever found in animals. Five mature BLPs (B1–B5) based on the amino acid sequences derived from the cDNA cloning were synthesized. In the in vitro myotropic contraction experiment, all synthesized BLPs displayed a stimulating effect toward rat stomach strips, except B4 and B5 which showed the opposite effect, suggesting that certain BLPs may act as antagonists of bombesin receptors while most other BLPs act as agonists. This finding will facilitate the finding of novel bombesin receptors and novel ligands of bombesin receptors. The diversity of amphibian BLPs and their precursors were also analyzed and results suggest that amphibian BLPs and corresponding precursors of various sizes and processing patterns can be used as markers of taxonomic and molecular phylogenetics. The remarkable similarity of preproregions gives rise to very different BLPs and 3′-terminal regions in distantly related frog species, suggesting that the corresponding genes form a multigene family originating from a common ancestor. The diversification of BLP loci could thus be part of an evolutionary strategy developed by amphibian species as a result of shifts to novel ecological niches when environmental factors change rapidly.

Antispasmodic, Analgesic, and Sedative Effects of Mormodica involucrata. Aqueous Extract in Rodents

Mormodica involucrata. E. Mey. ex Sond (Curcubitaceae; balsamina) is used in Swaziland traditional medicine for treating diabetes, intestinal disorders, and also for culinary purposes. At concentrations of 150 and 300 mg/mL, the extract significantly inhibited acetylcholine-induced contractions of the rat stomach strip (RSS) by 15 ± 1.0% and 25 ± 1.5%, respectively (p < 0.05, n = 6). The action of the extract was reversed by mevinphos 10−9 M, an organophosphate anticholinesterase, and potentiated acetylcholine-induced contractile effects on RSS. In the analgesic study, the extract at 55–75 mg/kg inhibited acetic acid–induced writhing and induced sleep in mice, and higher concentrations of the extract in the range 350–480 mg/kg caused death within 1 h of i.p. administration in 20% and 100%, respectively (p < 0.05, n = 10 per treatment). These results show that M. involucrate. possesses antispasmodic, analgesic, and sedative effects in rodents.

Serotonin and sensory signalling from the gastrointestinal lumen

Serotonin and sensory signalling from the gastrointestinal lumen

Cloning of novel bombesin precursor cDNAs from skin of Bombina maxima

Amphibian skin is a rich resource of bioactive peptides like proline-rich bombesin from frog Bombina maxima. A novel cDNA clone encoding a precursor protein that comprises proline-rich bombesin and a novel peptide, designated as bombestatin, was isolated from a skin cDNA library of B. maxima. The predicted primary structure of the novel peptide is WEVLLNVALIRLELLSCRSSKDQDQKESCGMHSW, in which two cysteines form a disulfide bond. A BLAST search of databases did not detect sequences with significant similarity. Bombestatin possesses dose-dependent contractile activity on rat stomach strips. The differences between cDNAs encoding PR-bombesin plus bombestatin and PR-bombesin alone are due to fragment insertions located in 3′-coding region and 3′-untranslational region, respectively.

Aspirin

Many memories flooded back as I read the historical sketch by Harvey Weiss [1]. Of course, I was his contemporary. In the summer of 1967 I was technical assistant to Hans Baumgartner (mentioned and present in the photograph in the article by Harvey) who had arrived at The Royal College of Surgeons in London to study the aggregation of rabbit platelets depleted of their dense granule content of serotonin by the use of reserpine. Part of my function was to ensure that the platelets contained little or none of it using a bioassay based on the principle that serotonin caused the contraction of the rat stomach strip.

A novel proline rich bombesin-related peptide (PR-bombesin) from toad Bombina maxima

A novel bombesin-related peptide was isolated from skin secretions of Chinese red belly toad Bombina maxima. Its primary structure was established as pGlu-Lys-Lys-Pro-Pro-Arg-Pro-Pro-Gln-Trp-Ala-Val-Gly-His-Phe-Met-NH2. The amino-terminal (N-terminal) 8-residue segment comprising four prolines and three basic residues is extensively different from bombesins from other Bombina species. The peptide was thus named proline rich bombesin (PR-bombesin). PR-bombesin was found to elicit concentration-dependent contractile effects in the rat stomach strip, with both increased potency and intrinsic activity as compared with those of [Leu13]bombesin. Analysis of different bombesin cDNA structures revealed that an 8 to 14- nucleotide fragment replacement in the peptide coding region (TGGGGAAT in the cDNAs of multiple bombesin forms from Bombina orientalis and CACCCCGGCCACCC in the cDNA of PR-bombesin) resulted in an unusual Pro-Pro-Arg-Pro-Pro motif in the N-terminal part of PR-bombesin.

Pharmacological Screening of a Methanol Extract from Mormodica charantia in Rodents

A methanol leaf extract of Mormodica charantia was evaluated for analgesic and contractile effects. The extract showed a significant reduction in writhing induced by acetic acid in mice and contractile effects on isolated rat stomach strip preparation, but reversed a dimethytubocurarine block of rat diaphragm muscle preparations, suggesting cholinomimetic and analgesic activities.

Pharmacological investigation of Ocimum gratissimum in rodents.

The pharmacological activities were screened of aqueous extracts of Ocimum gratissimum in isolated rabbit jejunum (IRJ); rat stomach strip (RSS); and also its analgesic properties in mice. The extract caused a dose dependent inhibition of the rabbit jejunum spontaneous pendular movement. The blocking effect on acetylcholine induced contraction was non-competitive in the rat stomach strip since maximum contractions were suppressed and no parallel shift was observed in the curve. The result of the analgesic study showed that the extract evoked a prolongation of reaction time of 85% ( p < 0. 05) over 20 min observation time with no overt signs of toxicity. These results suggest the presence of analgesic and spasmolytic activities.

Pharmacological investigation of Ocimum gratissimum in rodents

The pharmacological activities were screened of aqueous extracts of Ocimum gratissimum in isolated rabbit jejunum (IRJ); rat stomach strip (RSS); and also its analgesic properties in mice. The extract caused a dose dependent inhibition of the rabbit jejunum spontaneous pendular movement. The blocking effect on acetylcholine induced contraction was non-competitive in the rat stomach strip since maximum contractions were suppressed and no parallel shift was observed in the curve. The result of the analgesic study showed that the extract evoked a prolongation of reaction time of 85% ( p < 0.05) over 20 min observation time with no overt signs of toxicity. These results suggest the presence of analgesic and spasmolytic activities. Copyright © 1999 John Wiley & Sons, Ltd.

Some pharmacological and toxicological studies on Balanites aegyptiaca bark.

The aqueous extract of Balanites aegyptiaca bark, which is used in Sudanese folk medicine in the treatment of jaundice, was without effect when studied on rabbit intestine, rabbit aortic strip, rat stomach strip, rat uterus and rat phrenic nerve-diaphragm in a dose up to 10 mg/mL gut bath. In a larger dose (25 mg) the extract decreased significantly the contractility and the rate of the isolated perfused rabbit heart. Administration of the aqueous extract to biliary duct-ligated rats, showed a dose-dependent significant decrease in serum bilirubin level. The chronic and subchronic toxicity investigations indicate the safety of the aqueous extract at a dose level which showed a significant decrease in serum bilirubin level in experimental obstructive jaundice in rats.

Some pharmacological and toxicological studies on Balanites aegyptiaca bark

The aqueous extract of Balanites aegyptiaca bark, which is used in Sudanese folk medicine in the treatment of jaundice, was without effect when studied on rabbit intestine, rabbit aortic strip, rat stomach strip, rat uterus and rat phrenic nerve–diaphragm in a dose up to 10 mg/mL gut bath. In a larger dose (25 mg) the extract decreased significantly the contractility and the rate of the isolated perfused rabbit heart. Administration of the aqueous extract to biliary duct-ligated rats, showed a dose-dependent significant decrease in serum bilirubin level. The chronic and subchronic toxicity investigations indicate the safety of the aqueous extract at a dose level which showed a significant decrease in serum bilirubin level in experimental obstructive jaundice in rats. Copyright © 1999 John Wiley & Sons, Ltd.

Thromboxane A2 receptor antagonism in man and rat by a sulphonylcyanoguanidine (BM-144) and a sulphonylurea (BM-500).

Torasemide, a loop diuretic, has been reported to relax dog coronary artery precontracted by thromboxane A2 (TXA2), an endogenous prostanoid involved in cardiovascular and pulmonary diseases. N-cyano-N'-[[4-(3'-methylphenylamino)pyrid-3-yl]sulphonyl] homopiperidinoamidine (BM-144) and N-isopropyl-N'-[5-nitro-2-(3'-methylphenylamino)-benzenesulphon yl]urea (BM-500), chemically related to torasemide, have been examined for their TXA2 antagonism. The affinity (IC50, the concentration resulting in 50% inhibition) of BM-144 and BM-500 for the TXA2 receptor of washed platelets from man was 0.28 and 0.079 microM, respectively. This is better than for sulotroban (IC50 = 0.93 microM) but less than for SQ-29548 (IC50 = 0.021 microM), two TXA2 antagonists used as reference. The aggregation of platelets from man induced by arachidonic acid was prevented by BM-144 (IC50 = 9.0 microM) and by BM-500 (IC50 = 14.2 microM). Similar results were obtained by use of U-46619, a TXA agonist, as aggregating agent (BM-144, IC50 = 12.9 microM and BM-500, IC50 = 9.9 microM). The contracting effect of U-46619 on rat stomach strip was abolished by BM-144 (IC50 = 1.01 microM) and BM-500 (IC50 = 2.54 microM). Both drugs (BM-144: IC50 = 0.12 microM and BM-500: IC50 = 0.19 microM) also relaxed rat aorta precontracted by U-46619; both were more potent than sulotroban (IC50 = 1.62 microM). The two torasemide derivatives (100 microM) did not significantly affect the myo-stimulating effect of some prostaglandins (PGE2, PGI2, PGF2alpha) or aorta contraction elicited by KCl (30 mM). They did not modify rat diuresis after administration of a 30-mg kg(-1) dose. In conclusion, BM-144 and BM-500 can be regarded as novel non-carboxylic TXA2 receptor antagonists and offer a novel template for the design of more potent molecules.

P–348 - The contractile effect of various agonists in the rat stomach strips.

P–348 - The contractile effect of various agonists in the rat stomach strips.

A sensitive method for the assay of 5‐hydroxytryptamine

Think of any part of the body and you can be sure that the pharmacologist has cut it out, put into an isolated organ bath, or perfused its vessels in order to study the effects of drugs. For bioassay, segments of the gastrointestinal tract or spirally-cut strips of vascular tissue have mainly been used. Such procedures are the backbone not only of bioassay but also of classical pharmacology. I returned from a two-year postdoc with Arnold Welch at Yale University to become senior lecturer in pharmacology at the Royal College of Surgeons of England, where Bill (later Sir William) Paton was Professor. In surveying the effects of drugs on the isolated stomachs of several laboratory species, I noticed that the white translucent part (as opposed to the thicker, pink, pyloric antrum) of the rat stomach was singularly sensitive to the contractor effects of 5-hydroxytryptamine (5-HT). In the paper I described this part as the fundus, but Brendan Whittle tells me it is the corpus. Happily, the preparation became known as the rat stomach strip (RSS). I decided to record from the more sensitive longitudinal muscle. The bag was opened down one side, the muscle cut in a zigzag fashion as if making a paper streamer and then pulled out, trimmed and its length recorded on a kymograph with a spring lever. The rat stomach strip was useful, not only for the assay of 5-HT, but also to compare the activities of many analogues of tryptamine (Vane, 1959; Handschumacher & Vane 1967). At this time, I had not been converted to Gaddum's superfusion technique and so I hung the RSS (which was usually 10–12 cm long) in a 5ml bath with rapid bubbling to ensure good mixing. Because the RSS had no rhythmic tone, a lever giving 16:1 magnification could be used. In order to shorten the time of relaxation in between contractions, the tissue was stretched by an extra weight to a predetermined length during the washing period. Later, my interests turned to the bioassay of other vasoactive substances and we found that the same tissue, now contracted by a constant concentration of 5HT in the bathing fluid, could be used to assay catecholamines by their relaxant effects (Armitage and Vane, 1964). We also demonstrated the sensitivity of the RSS to prostaglandins and showed the release of a prostaglandin (wrongly identified as PGE1) from the same tissue (Bennett, Friedman and Vane, 1967). The rat stomach strip has stood me in good stead over 40 years, contributing to several discoveries, such as the mode of action of aspirin (inhibition of the biosynthesis of prostaglandins) and the discovery of prostacyclin. It is continuing to do so in the William Harvey Research Institute (now 10 years old), where we are studying with renewed intensity the vasoactive hormones released by endothelial cells such as prostacyclin, endothelium-derived relaxing factor (nitric oxide) and endothelin.