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Biomedical subjects

K Kowalewski

Publications and source records attributed to K Kowalewski.

At least 55 records · Page 3Linked to original sources
PubMed1975

Electrical and mechanical activity of the isolated canine stomach perfused with homologous, in vitro, oxygenated blood.

Electrical and mechanical activity was recorded from six totally isolated canine stomachs perfused with homologous blood oxygenated in vitro. Reactions to electrical vagal stimulation to cholinergic drugs and to pentagastrin were recorded. Electrical control activity, electrical response activity and mechanical response of isolated stomachs, observed in this in vitro system, were identical to those found in canine-isolated stomachs perfused with cross-circulated blood of living animals. It appears that when a living animal is included in the perfusion system of the isolated stomach, drugs used for gastric stimulation are rapidly metabolized and, due to this physiological clearance, repeated injections of stimulants can be given for several hours. Using the in vitro perfusion system, as in this experiment, injected drugs accumulate in the perfusion blood, as no clearance mechanism is available. Partial or total exchange of perfusion blood is therefore recommended. With these reservations, the in vitro system appears to be an easy method for the study of nonstimulated and stimulated electrical and mechanical activity of the totally isolated canine stomach.

Animals↗
PubMed1975

Effect of metoclopramide on myoelectrical and mechanical activity of the isolated canine stomach perfused extracorporeally.

Totally isolated whole canine stomachs perfused, ex vivo, with homologous blood of living supporting dogs were used for recording of myoelectrical mechanical activities. Drugs were administered directly into the arterial system of the isolated stomachs either as flash injections or as constant infusions. Flash injection of metoclopramide (Maxeran) led to the response activity (spiking) and associated mechanical response. Electrical control activity was also affected by Maxeran: the changes consisted of premature control activity and uncoupling. Similar reactions were observed after flash injections of methacholine, pentagastrin or electrical stimulation of the Latarjet nerve. These reactions were dose-dependent. Tetrodotoxin, atropine, hexamethonium and glucagon, when given as a constant infusion, did inhibit the action of Maxeran on myoelectrical and mechanical activities of the isolated stomach. Inhibition of the responses to Maxeran by atropine and tetrodotoxin implicates acetylcholine in the mediation of these responses. The ability of hexamethonium to diminish the response to Maxeran suggests that a locus of action may be at both pre- and post-ganglionic sites of the intramural plexus. Exact receptors of this action are not demonstrated by this study.

Animals↗
PubMed1975

The effect of secretin on pentagastrin-stimulated secretion of gastric pepsin and acid in rats.

Rats with chronic gastric fistulas were stimulated for 12 or 24 h with constant intravenous infusion of pentagastrin. When secretin was also infused for the last half period of the experiment, respectively, 6 or 12 h, the volume of gastric secretion and HCl output were significantly reduced but the concentration of pepsin was significantly increased. The dissociated effect of secretin on gastric acid and pepsin secretion reported previously in man, dog and cat was also found in the rat.

Animals↗
PubMed1975

Simultaneous study of gastric and pancreatic secretion in a preparation perfused ex vivo.

A canine gastroduodenopancreatic block was isolated and perfused ex vivo with homologous blood. This preparation allowed a simultaneous collection of gastric and pancreatic secretion under various conditions of stimulation. To stimulate gastric secretion, pentagastrin, bethanechol chloride or histamine was infused intra-arterially during a six to eight hour period, or both vagi were electrically stimulated. To stimulate pancreatic secretion, secretin was infused by the same method. Secretin infusion inhibited gastric juice volume and acid output by stimulated stomachs and induced an increase in pepsin concentration. Secretin infusion also resulted in a significant increase of flow of pancreatic juice and in both concentration and output of pancreatic secretion of bicarbonate. Arterial perfusion pressure and peripheral vascular resistance of this ex vivo preparation were significantly reduced by secretin. The method described permits the simultaneous study of the secretory function of the stomach and pancreas as well as the evaluation of biochemical changes of perfusion blood and hemodynamic changes in the circuit. Easy accessibility of the vessels and vagus branches also allows direct infusion of drugs and placement of stimulation electrodes.

Animals↗
PubMed1975

Effect of glucagon on myoelectrical and mechanical activity recorded from the isolated homologous perfused canine stomach.

Totally isolated whole canine stomachs, perfused ex vivo with homologous blood, were used for recording of myoelectrical and mechanical activity. Hormones were administered into the arterial system of the isolated stomach. Pentagastrin, methacholine and electrical stimulation induced premature control potentials with uncoupling of the normal, phase locked, pattern of electrical control activity and also stimulated mechanical activity. Electrical response activity was also present. When the three modes of stimulation were applied during the infusion of glucagon, a marked inhibitory effect was observed. This effect consisted of inhibition of mechanical activity and of electrical response activity. Glucagon also decreased, but did not suppress the changes in electrical control activity observed after electrical stimulation and after injection of pentagastrin or methacholine into the gastric artery of the isolated stomach. During infusion of glucagon, the mean gastric arterial perfusion pressure and gastric peripheral vascular resistance were reduced.

Animals↗
PubMed1975

Effect of ischemic anoxia on myoelectrical and mechanical activity of the totally isolated canine stomach.

Electrical and mechanical activities were recorded from the totally isolated canine stomach perfused with homologous blood of a living oxygenator-supported dog. Stagnant ischemic anoxia was induced by closing inflow and outflow blood from the isolated organ for various periods of time up to four hours. Recording of electrical and mechanical activity was performed prior to, during, and after the anoxic periods. After a given period of ischemia, blood was recirculated for ten minutes, and the pentagastrin was injected into the gastric artery. After up to three hours of anoxia, stomachs were able to show recordable electrical activity when perfused for ten minutes with homologous blood. Up to this period of three hours, stomachs also responded to the injection of pentagastrin. Pentagastrin accelerated the normalization of electrical and mechanical activity of previously anoxic stomachs. After 3.5 to 4.0 hours of anoxia, recirculation of blood through the stomach and injection of pentagastrin had no effect on electrical and mechanical activity of the gastric musculature.

Animals↗