Effect of environment on temperatures in the viscera of the dog

Abstract

the INTRODUC TIONThe influence of ambient temperatures on the pattern of temperature distribution within the viscera has been investigated by a number of workers. Stupfel and Severinghaus (1956) for instance, reported an increase in dog stomach to rectum thermal gradient during immersion hypothermia. Similarly Grayson and Kinnear (1962) observed that in a hot tropical (Nigeria) environment the liver and rectal temperatures of human subjects were similar, whereas on cooling the environment the liver assumed an equilibrium temperature averaging 0.44°C below rectal. This temperature differential was similar to the liverrectam gradient of between 0.2 ° and 0, 6°C observed in human subjects living in a temperate environment by Graf, Porje and Allgoth (1955).Later, Grayson, Irvine and Kinnear {1966) showed that the gastro-intestinal tract of monkeys, dogs and of man was a substantial producer of heat, the bowel lumen being about 0.6°C hotter than the aortic blood. The liver, in fact, had a lower total heat production and, being cooled by hepatic arterial blood was at a lower temperature. These workers attributed the temperature changes which took place on cooling to alterations in blood flow distribution between bowel and liver and discounted the possibility of changes in heat production. However, this question has now been re-examined and the purpose of this paper is to present data showing possible metabolic changes in some parts of the gastro-intestinal tract in response to changing environmental temperature. ME THODSMongrel dogs, 8 to 14 kg, were fasted for 24 to 48 hours prior to the experiment. They were lightly anaesthetized with sodium pentobarbitone (36 mg/kg body weight, ip).Temperatures were measured thermo-electrically (Grayson, Irvine and Kinnear, 1966) from the lumen of the stomach, duodenum, ileum, large intestine and the rectum. The gastric applicator was introduced through the mouth, the intestinal applicators were inserted by direct vision, after laporotomy, through small incision penetrating the bowel and closed around the probe by pursestring sutures.Aortic temperature was recorded from a probe passed through the femoral artery to a position near the origin of the eoelaic artery. Rectal temperature was recorded from an average depth of 8 era. from the anal orifice. The abdomen was closed in two layers with continuous sutures.The animals were supported on a light frame which permitted free circulation of room air.

The ingestible telemetric body core temperature sensor: a review of validity and exercise applications

“…33 34 Furthermore, temperature gradients along the gastrointestinal tract were evident, with the duodenum and ileum exhibiting significantly higher (p,0.05) temperatures than the stomach, large intestine and rectum. 34 These findings are in line with the observations of the latter three studies in table 2, [17][18][19] showing significantly higher T intestinal versus T rectal and significantly higher T intestinal versus T oesophageal . 17 This indirect evidence suggests the existence of a temperature gradient along the gastrointestinal tract (ie, from stomach/small intestine/large intestine to rectum), and from the gastrointestinal tract to central blood in humans; however, the magnitude of the gradient does not seem to be affected by movement of the ingestible sensor along the gastrointestinal tract.…”

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“…Further evidence is available from animal studies which demonstrate a temperature gradient along with GI tract as duodenum and ilium temperatures were significantly higher than stomach, large intestine and rectum (19). As a result one possible explanation for the observed variation in intestinal temperature is that variability in intestinal peristaltic velocity advances the pill to areas of the GI tract which may exhibit different temperatures.…”

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“…Wilkinson et al [39] Several human studies provide indirect evidence to support the notion of a temperature gradient along the GI tract as GI pill temperature is consistently higher than rectal temperature [5]. Further evidence is available from animal studies which demonstrate a temperature gradient along with GI tract as duodenum and ilium temperatures were significantly higher than stomach, large intestine and rectum [259]. As a result, one possible explanation for the observed variation in intestinal temperature is that variability in intestinal peristaltic velocity advances the pill to areas of the GI tract which may exhibit different temperatures.…”