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Biomedical subjects

K Kowalewski

Publications and source records attributed to K Kowalewski.

At least 37 records · Page 2Linked to original sources
PubMed1977

Gastric mucinous secretion under various conditions of stimulation in hypothyroid dogs.

Principal glycoproteins and amino acids of the secretions from Heidenhain pouches, were studied in normothyroid and hypothyroid Labrador dogs in the resting state, following injection of pentagastrin, histamine and after feeding. Hypothyroidism was produced by total thyroidectomy and chronic treatment with thiouracil. All samples showed the presence of galactose, glucosamine, galactosamine, fucose, mannose, uronic acid and sulfate. Galactose and glucosamine were found in equimolar amounts and the galactose to galactosamine ratio was 2:1. Concentrations of most carbohydrate components studied were higher in normothyroid than in hypothyroid dogs. Concentrations of most amino acids analyzed were also higher in normothyroid than in hypothyroid dogs, following stimulation with secretagogues.

Amino Acids↗
PubMed1977

Effect of secretin on myoelectrical and mechanical activity of the isolated canine stomach perfused ex vivo.

Totally isolated whole canine stomachs, perfused ex vivo with homologous blood, were used for recording of myoelectrical and mechanical activity prior to and following the injection of secretin. Secretin was given as flash injections (0.5 - 32 U) or constant infusions (60 U/h). Background stimulation of stomachs was obtained by intragastric instillation of fluid, by the infusion of pentagastrin or bethanechol chloride, and by electrical stimulation of the Latarjet branch of the vagus nerve. Hormones were injected into the gastric arterial circulation. Secretin had no effect on the frequency of electrical control activity. Secretin inhibited electrical response activity when injected against the background of electrical vagus stimulation. Secretin also inhibited or decreased mechanical activity of the gastric antrum, recorded at the site of the antral strain gauge.

Action Potentials↗
PubMed1977

Electrical and mechanical activity of isolated canine stomach perfused with fluorocarbon emulsion.

Electrical and mechanical activities were recorded from the isolated canine stomach perfused with fluorocarbon emulsion and oxygenated in vitro. This preliminary experiment was undertaken to determine whether or not these activities can be preserved during extracorporeal bloodless perfusion using a perfusate containing only an oxygen carrier, fluorocarbon and a simulated physiologic salt solution of some electrolytes. We found that electrical control activity of stomachs so perfused was identical with that found under in vivo conditions. The electrical and mechanical response of these stomachs to intra-arterially injected methacholine and pentagastrin and to electrical stimulation of the vagus nerve suggested that the function of the muscular and intramural plexus layers of the gastric wall remained normal. It was also observed that the frequency of the cycles of electrical control activity and the amplitude of antral contractions were significantly increased, when pO2 of the circulating perfusate rose. Results of the biochemical studies of the perfusate suggested utilization of some of its components for the metabolic needs of the perfused organ. The gastric secretion was alkaline and contained particles of fluorocarbon emulsion.

Animals↗
PubMed1976

Effect of ischemic anoxia on electrical and mechanical activity of the totally isolated porcine stomach.

Electrical and mechanical activity were recorded from totally isolated whole porcine stomachs perfused with homologous blood. Stagnant, complete ischemia was then produced by closing the gastric artery and vein for various periods of time up to 3 h. After a given period of ischemia, blood was recirculated for 10 min and then pentagastrin was injected into the gastric artery. The vagus nerve was also electrically stimulated at various stages of anoxia and recirculation. After up to 90 min of ischemia, stomachs were able to demonstrate electrical control activity of low frequency after 10 min of blood recirculation. After injection of pentagastrin, electrical control activity rapidly became normal. When ischemia lasted 120 min or longer, recirculation of blood did not induce reappearance of electrical control activity, but pentagastrin injection produced a normal response. After ischemia of 240 min duration or longer, recirculation and pentagastrin had no effect. In previously ischemic stomachs the response to vagal stimulation occurred only in the stomachs responding to pentagastrin.

Animals↗
PubMed1976

Mucinous secretion from canine Heidenhain pouch after stimulation with food, pentagastrin and histamine.

Principal glycoproteins and amino acids were determined in gastric juice obtained from Heidenhain pouches of Labrador pure-bred dogs. Secretions were stimulated by food, pentagastrin or histamine. Non-stimulated fasting secretions served as controls. All samples showed the presence of galactose, glucosamine, galactosamine, fucose, glucose, mannose and sulfate. Galactose and glucosamine were found in equimolar amount and the galactose to galactosamine ratio was 2:1. Concentrations of most carbohydrate components studied were higher in fasting than in stimulated secretions. Outputs of some of these components were lower in fasting than in stimulated secretions. Modes of stimulation used did not significantly affect the outputs of principal glycoproteins studied. Compared with human gastric secretions studied by others, using similar methods, certain differences were found particularly in the relationship between some carbohydrate components and between amino acids.

Amino Acids↗
PubMed1976

Effect of bombesin, a natural tetradecapeptide, on myoelectrical and mechanical activity of isolated, ex vivo perfused, canine stomach.

Electrical and mechanical activity were recorded from the canine stomach, isolated and ex vivo perfused with homologous blood. The action of Bombesin, a natural tetradecapeptide, was compared with the action of pentagastrin, methacholine and electrical stimulation on the electrical and mechanical activity of this isolated preparation. All drugs used and vagal stimulation resulted in premature control potentials, uncoupling of the normal phase locked pattern of electrical control activity, appearance of response activity and appearance of mechanical reaction. These responses were blocked or decreased by atropine, tetrodotoxin and hexamethonium. It appears that the neural release of acetylcholine is implicated in the mechanism of action of Bombesin gastrointestinal motility.

Action Potentials↗
PubMed1976

Effect of glucagon on myoelectrical and mechnical activity of the isolated homologous perfused porcine stomach.

Totally isolated whole porcine stomachs, perfused extracorporeally with homologous blood, were used for recording gastric electrical and mechanical activity. Hormones Hormones were administered into the arterial system of the isolated organ. Pentagastrin, methacholine and electrical stimulation of the vagus nerve induced premature control potentials with uncoupling of the normal, phase-locked, pattern of electrical control activity and also produced electrical response activity and mechanical reaction. When glucagon was infused a progressive decrease of frequency of the cycles of electrical control activity was observed. Glucagon also abolished electrical response activity and mechanical activity, if they were present prior to hormone infusion. When pentagastrin, methacholine or electrical stimulation were applied during the infusion of glucagon, the responses to these stimulants were decreased or absent. The inhibitory action of glucagon was dependent on the duration of infusion of this hormone and lasted for 30-45 min after the infusion was discontinued. During infusion of glucagon the mean gastric arterial perfusion pressure and gastric peripheral vascular resistance were reduced.

Action Potentials↗
PubMed1976

The effect of aminophylline on pentagastrin-induced secretion and motor activity of totally isolated canine stomach perfused extracorporeally.

Totally isolated canine stomachs, perfused extracorporeally with homologous blood of living oxygenerator-dogs, were used for the study of gastric secretion. Aminophylline and pentagastrin were infused into the gastric arterial system separately or combined. Aminophylline, infused alone, did not stimulate gastric secretion. However when aminophylline was administered during the infusion of pentagastrin, it significantly augmented the action of this peptide on gastric acid secretion. Aminophylline did not alter myoelectrical and mechanical response to pentagastrin nor did it affect the myoelectrical activity of the nonstimulated stomach. Gastric arterial perfusion pressure and gastric peripheral resistance were reduced during infusion of aminophylline alone or in combination with pentagastrin.

Aminophylline↗
PubMed1976

Effects of calcium infusion on secretion and motor activity of totally isolated canine stomach perfused with homologous blood.

Isolated, ex vivo perfused, canine stomachs were used for this study. Gastric secretion, myoelectrical activity and mechanical activity were recorded during stimulation of gastric function with pentagastrin or histamine alone or combined with calcium gluconate. Secretagogues and calcium were infused into the gastric arterial circulation. Hypercalcemia induced significant inhibition of pentagastrin, stimulated gastric secretion, but did not affect the secretion stimulated by histamine. Hypercalcemia also induced an increase of frequency of cycles of electrical control activity and a decrease of mechanical activity of the gastric antrum. The effect of hypercalcemia on gastric motor function was similar in the nonstimulated stomach and during the infusion of secretagogues used in this experiment.

Action Potentials↗
PubMed1976

Gastric secretory response to cholinergic stimulation in rats chronically pretreated with pentagastrin or histamine in depot form.

Rats pretreated by daily depot injections of pentagastric for 24 days, responded with a significant increase of gastric secretion volume, and HC1 concentration and output, when infused intravenously with bethanechol chloride. In these rats, the total weight of the stomach and the height of the fundic mucosa were also increased. Pretreatment with histamine had no effect on rat gastric tissue or gastric secretion, under identical conditions of stimulation.

Animals↗
PubMed1976

Histamine-stimulated gastric secretion in rats with chronic renal insufficiency.

Chronic uremia was induced by long-term maintenance of rats which had undergone sub-total nephrectomy, with sham-operated rats serving as controls. Chronic gastric cannulas and chronic vascular catheters (vena cava) were installed and the rats were stimulated with intravenous infusion of histamine. In uremic rats, the volume of gastric juice, output of HC1 and H+ concentration were significantly higher than in the controls during the 6-hour secretion experiments.

Animals↗
PubMed1976

Effect of age and sex on histamine-induced gastric secretion in laboratory rats.

The effect of age and sex on histamine-stimulated 24-hr gastric secretion was assessed in the rat. Secretion tests were done in rats of both sexes at 3, 6, 9, 12, 18, and 24 mo of age. The highest 24-hr volume and acid output of gastric secretion was found in both sexes in the 9-mo age group. When related to body weight the highest 24-hr gastric secretion and acid output was found in 6-mo-old males and in 9-mo-old females. This observation may have practical value when the rat is selected as an experimental tool for the study of gastric secretory function.

Age Factors↗
PubMed1975

Mucinous secretion of totally isolated porcine stomach perfused with homologous blood.

Principal glycoproteins and amino acids were determined in porcine gastric juice obtained from totally isolated stomachs perfused extracorporeally with homologous blood. Acid juices collected during prolonged stimulation of stomachs with histamine or pentagastrin, infused into gastric arteries, were used. All samples showed the presence of glactose, glucosamine, galactosamine, fucose, mannose and sulphate. Galactose and glucosamine were found in equimolar amounts and the galactose to galactosamine ratio was, in most samples, 2:1. Compared with human non-stimulated gastric juice studied by others, marked differences were found in the relationship between carbohydrate components and between amino acids. Porcine gastric juice contained much more protein than human gastric juice. Some characteristics of porcine mucinous secretion may be due to conditions of juice collection from the isolated gastric preparation.

Amino Acids↗
PubMed1975

Effect of release of endogenous gastrin on myoelectrical and mechanical activity of isolated canine stomach.

The myoelectrical and mechanical activities of the totally isolated, canine stomachs were recorded using five sets of bipolar silver-wire electrodes and one strain gauge. Stomachs were perfused extracorporeally with the blood of living supporting dogs which served as oxygenators and dialysers. Each supporting dog had a permanent antral pouch, accessible for the purpose of irrigation. To suppress the release of endogenous gastrin, this antral pouch and the antrum of the ex vivo stomach were irrigated with acid (pH 3). To induce the release of gastrin, one or both antra were irrigated with 0.2-percent acetylcholine or with 1 M glycine. To compare the action of endogenous gastrin with exogenous gastrin-like peptide, pentagastrin was infused into the gastric artery in doses of 4 mug/h and 8 mug/h. Control recordings were done during the acid irrigation. Endogenous gastrin released from antra by acetylcholine or glycine caused identical changes in the recordings as exogenous pentagastrin. There was a marked increase in the frequency of electrical control activity and of gastric contractions recorded as increased mechanical response. The results indicate that the ex vivo stomach can be used for study of the effect of endogenous gastrin musculature activity under the experimental conditions described.

Acetylcholine↗
PubMed1975

The effect of drugs on the electrical and mechanical activity of the isolated porcine stomach.

Electrical and mechanical activity was recorded from totally isoltted porcine stomachs perfused with homologous blood, The electrical control activity, response activity, and mechanical reaction to various hormones and drugs stimulationg these activities were recorded. The drugs were injected directly into the gastric artery of the isolated organ. Normal response to cholinergic stimulants and to pentagastrin was observed. The effect of blockers such as atropine, hexamethonium and tetrodotosin on the action of stimulants was also assessed. The results of this study suggest that the release of acetylcholine is involved in the mechanism of action of pentagastrin. They also demonstrate the usefulness of the isolated porcine stomach approach to the study of gastric myoelectrical and mechanical activity.

Acetylcholine↗
PubMed1975

Effect of prostaglandin-E2 on myoelectrical and mechanical activity of totally isolated, ex-vivo-perfused, canine stomach.

This study was concerned with the effects of prostaglandin-E2 (PGE2) on myoelectrical and mechanical activity of the isolated, homologous perfused canine stomach. A flash injection of 25 mug of PGE2 into the gastric artery led to production of premature control potentials, uncoupling of electrical control activity (ECA) and to a weak mechanical response of short duration. After vagal stimulation of the nerve of Latarjet, or after flash injection of pentagastrin (2.5 mug) or of methacholine (5 mug), similar changes in ECA were observed, but mechanical response corresponding to antral contractions was very pronounced. Prolonged infusion of PGE2 (500 mug/h) induced a marked increase of ECA frequency. A similar effect on ECA frequency was observed during infusion of pentagastrin (32 mug/h). Infusion of PGE2 abolished, but infusion of pentagastrin stimulated, mechanical response. Effects of a flash injection of PGE2 on electrical activity were reduced by hexamethonium and abolished by tetrodotoxin and atropine. The action of the blocking agents on PGE2-induced changes in ECA was similar to the action of these blockers on gastric myoelectrical activity, stimulated vagally or by injection of pentagastrin and methacholine. Infusion of PGE2 induced a marked reduction in gastric peripheral vascular resistance, but no time-correlation between hemodynamic effects of PGE2 and its action of gastric musculature was noted.

Action Potentials↗