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Biomedical subjects

M F Tansy

Publications and source records attributed to M F Tansy.

At least 55 records · Page 3Linked to original sources
PubMed1976

A functional description of the canine choledochoduodenal flutter valve.

Forward- and reverse-opening pressures of the choledochoduodenal junction were measured in anesthetized, vagotomized dogs. Mean reverse-opening pressures were found to be significantly greater in most cases including those following the intraductal administration of vasoactive agents which are known to significantly influence mean forward-opening pressures. The polypeptides CCK-PZ and CCK-C8 were ineffective in reducing mean forward-opening pressures regardless of the route of administration. Previously published observations have indicated that mean forward-opening pressures are also unaffected by nervous activity. It is concluded that the canine choledochoduodenal junction possesses the physical and functional properties of a passive flutter valve during duodenal relaxation.

Animals↗
PubMed1975

Technique for assessment of local effects of substances found in bile upon opening pressure of choledochoduodenal junction.

An assessment of the localized influences of various chemicals found in bile was made by applying them to the interior of the canine choledochoduodenal junction. Test agents were isolated by air bubbles and introduced into the terminal lumen of the intramural portion of the common bile duct via the pressure measurement catheter; they remained in the duct for approximately 1.5 min. The system was flushed and opening pressures were then measured. Responses were measured in terms of alterations in ductal opening pressures generated by a linear pressure ramp. Histamine, serotonin, and bethanechol markedly increased ductal opening pressures, whereas epinephrine and norepinephrine decreased opening pressures. None of the agents affected either cardiovascular or small intestinal motor activity in the vicinity of the sphincter when administered in the manner. The results suggest that the presence in bile of certain neurohumoral transmitters and neurohumoral-like agents may directly affect the canine choledochoduodenal sphincter function.

Animals↗
PubMed1975

The mucosal lining of the intramural common bile duct as a determinant of ductal opening pressure.

Microanatomical evidence is presented which shows that the lumen of the intraduodenal portion of the common bile duct is almost completely filled by folds of a highly vascularized mucosa in the dog, cat, rabbit, and human. These folds are most apparent near the intraduodenal ductal orifice, where they almost completely occlude the lumen. Physiological data are presented which indicate that changes in systemic arterial blood pressure are associated with changes in the opening pressures of the choledochoduodenal junction of the cat and dog, which vary in the same direction. Experimental results indicate that bile duct opening pressures of these two species are increased by the intraductal administration of histamine and reduced by the intraductal administration of norepinephrine. A histological examination of the intraductal mucosal folds in this area, subsequent to the administration of the elevating agent, revealed a marked presence of vascular engorgement. It is concluded that the most significant determinant of changes in ductal opening pressures in the cat and dog is probably the state of the mucosal vasculature of the terminal portion of the common bile duct.

Animals↗
PubMed1975

Evidence of nonvagal neural stimulation of canine gastric acid secretion.

In this study, we confirmed our original findings that central vagus stimulation is significantly associated with a subsequent increase in gastric mucus secretion. Central vagus stimulation following phenoxybenzamine hydrochloride administration was associated significantly with protracted elevations in secretory volume and titratable acid. We were unable to conclude that phenoxybenzamine itself in several pharmacologic dosages was associated with an increase in titratable acid. The acid secretory responses could be abolished by transection of the splanchnic nerves. Electrical stimulation of the peripheral part of the splanchnic nerve following administration of phenoxybenzamine was also associated with significant increases in secretory volume and titrable acidity. These secretory responses were not blocked by atropine but were diminished by burimamide. It is concluded that, in the dog, a largely heretofore unsuspected second neural pathway exists which is capable of influencing gastric acid secretion.

Animals↗
PubMed1975

A demonstration of microvilli on the luminal surfaces of epithelial cells of the canine extrahepatic biliary tract.

Micromorphologic evidence is presented which indicates that in the dog the lining epitheliums of the intramural portion of the common bile duct and proximal part of the cystic duct are organized into convoluted folds. The mucosal lining of the extramural portion of the common bile duct appears to contain simple crypt structures. The mucosal surface of the hepatic duct is characterized by parallel ridges, longitudinally aligned with the long axis of the duct. The epithelial cells of the entire canine extrahepatic biliary tree present a topographic-dome shaped appearance, and their luminal surfaces are densely covered with microvilli.

Animals↗