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Biomedical subjects

D L Innes

Publications and source records attributed to D L Innes.

17 recordsLinked to original sources
PubMed1981

Central nervous system effects of methyl methacrylate vapor.

Inhalation experiments were conducted by exposing mature male Sprague-Dawley rats to methyl methacrylate (MMA) monomer vapor in air. The effects upon central neuronal activity associated with acute exposures of chloralose-urethanized rats to monomeric MMA vapor concentrations are summarized in this report. The most remarkable and readily apparent phenomenon was the depression of multiple-unit electrical activity in the lateral hypothalamus and ventral hippocampus of rats which were exposed to 400 ppm of MMA in air for 60 min. In marked contrast, recordings made from the parietal cortex, cerebellum, dorsal hippocampus, medial amygdala, ventral medial hypothalamus, anterior hypothalamus, septum, and mammillary body following comparable exposures showed insignificant changes in multiple-unit electrical activity.

Animals↗
PubMed1980

Gastric mucosal ulceration associated with electrochemical stimulation of the limbic brain.

Electrochemical stimulation of the medial amygdaloid nucleus of chloralose-urethan anesthetized rats of either sex leads uniformly to the appearance of gastric ulcers within four hours. The effect is not present with sodium pentobarbital anesthesia, vagotomy, or following pretreatment with atropine sulfate or tetraethylammonium chloride (TEA). The effect is reduced by chlorpromazine and is not blocked by cimetidine in dosages as high as 160 mg/kg. It is concluded that the vagus nerve is a necessary component of the response and that the response appears to be cholinergic.

Animals↗
PubMed1979

Glycemic responses induced by hypothalamic stimulation.

Serum Glucose concentrations were measured before and after electrical stimulation in the ventromedial and supramamillary nuclei of the hypothalamus. 27 fed rats of both sexes were anesthetized with Sodium Pentobarbital. A 36 gauge nichrome electrode was positioned stereotaxically within the rat brain. Stimulus parameters were 0.1 mA using a 1.0 ms biphasic square wave applied at a rate of 50 Hz for 3 min. Blood samples were removed from the left carotid artery at -20 and 0 min pre-stimulation and also at 5, 10 and 15 min post stimulation. Serum glucose concentrations were determined by enzymatic estimation with hexokinase. Electrical stimulation of either the ventromedial or supramamillary nuclei produced statistically significant elevations in serum glucose concentrations, whereas stimulation in areas immediately surrounding both nuclei did not produce any significant changes in serum glucose concentrations. These results suggest that both nuclei may be involved in the regulation of serum glucose concentrations.

Animals↗
PubMed1977

GI pharmacology of polyethyleneimine II: motor activity in anesthetized dogs.

The effects of orally and intravenously administered doses of polyethyleneimine were observed in 18 chloralose-urethan-anesthetized dogs. Polyethyleneimine produced an initial augmentation of rhythmic segmenting gastric antral contractions, a copious flow of gastric mucus, increased segmenting and propulsive activities of the small and large intestines, and occasional micturition and defecation. The gastric corpus and fundic regions became relaxed and enlarged. These events were associated with the prompt appearance of retching. The retching response to oral administration could only be abolished by bilateral vagotomy or bilateral sympathectomy. The skeletal muscle component of retching was blocked by tubocurarine. Intravenous administration of chlorpromazine blocked the retching response and gastric corporal atonia to either intravenous or oral doses of polyethyleneimine. Either oral or intravenous administration of polyethyleneimine produced no detectable changes in the lead II ECG but was associated with marked transient reductions in both mean and pulsatile arterial blood pressures. These depressor effects showed clear tachyphylaxis. In all cases where GI effects were noted, respiration was augmented and erratic in a manner associated with the retching responses.

Animals↗
PubMed1977

The occlusive competence of the duodenal orifice of the canine pancreatic duct.

Observations by scanning electron microscopy indicate that the mucosa of the terminal part of the major pancreatic duct of the dog is organized into numerous, highly convoluted folds. The individual mucosal cells are tall, columnar and studded with numerous microvilli. These folds are highly vascularized. The intraluminal administration of bethanechol and norepinephrine is associated with subsequent increases and decreases of mean opening pressures. Mean opening pressures were not observed to be associated with autonomic nervous activity that was unaccompanied by changes in systemic arterial pressure. It is concluded that the terminal portion of the canine major pancreatic duct probably acts as a passive valve, the occlusive competence of which is influenced by the status of the vasculature of the lining mucosa in this region.

Animals↗
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

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↗