Heat production in the gastro‐intestinal tract of the dog

Durotoye, A. O.; Grayson, J.

doi:10.1113/jphysiol.1971.sp009441

Cited by 22 publications

(15 citation statements)

References 5 publications

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“…However, we should note that duodenal and jejunal blood flows are comparable (Delaney & Custer, 1965). Our own work also indicates that resting heat production is similar in the two regions (Durotoye & Grayson, 1971). However, these observations may not be relevant.…”

Section: Discussionmentioning

confidence: 60%

Effect of nicotine on blood flow, oxygen consumption and glucose uptake in the canine small intestine

Grayson

Oyebola

1985

British J Pharmacology

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1 Resting blood flow, arterio-venous glucose and oxygen (A-V)02 differences, glucose uptake and oxygen consumption by a segment of the upper jejunum were measured in anaesthetized dogs. Systemic arterial pressure was also measured. 2 The effect of nicotine infusion (25 pg kg-' i.v., over 10 min) on these measurements was recorded in untreated dogs, in dogs treated with propranolol (0.5 mg kg-') to produce P-adrenoceptor blockade and in dogs after a,-adrenoceptor blockade with prazosin (0.2 mg kg-').3 Nicotine cause a significant pressor response during infusion and a hypotensive response during the post infusion period. Propranolol did not significantly affect these results. Jejunal blood flow increased in the first half of nicotine infusion in both the untreated and P-blocked animals. Vascular resistance was reduced during nicotine infusion and the decrease persisted post infusion in the P-blocked group. 4 In the untreated group (A-V)O2 was significantly reduced during the first 5min of nicotine infusion, thereafter it returned to control levels, then rose significantly above control level, post infusion. P-Adrenoceptor blockade had little effect on these responses to nicotine. When oxygen consumption was calculated it was found that nicotine had little effect during or after infusion. 5 Nictine caused significant hyperglycaemia during and for about 1 h after infusion. Tissue release of glucose was occasionally observed following the infusion. 13-Adrenoceptor blockade reduced the hyperglycaemia caused by nicotine. P-Blockade alone increased glucose uptake and nicotine caused a further three to four fold increase. Prazosin abolished the effects that were observed in the untreated and the a-blocked animals. 6 The present findings, related to our previous observations on the effects of catecholamines on glucose uptake by the bowel, are consistent with the hypothesis that nicotine has its action on bowel glucose uptake or release through its well-established action in releasing catecholamines and in activating P-adrenoceptors. The responses are not related to oxygen utilization.

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Section: Discussionmentioning

confidence: 60%

Effect of nicotine on blood flow, oxygen consumption and glucose uptake in the canine small intestine

Grayson

Oyebola

1985

British J Pharmacology

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“…It has become apparent in r e c e n t y e a r s that the metabolic activity of the bowel in t e r m s other than active transport or smooth muscle activity is g r e a t e r than had been previously thought likely (Durotoye and Grayson, 1971;Hartialla, 1968). The p r e s e n t authors have more recently shown (unpublished) a close link with the l i v e r in r e s p e c t of glucose metabolism, with insulin and glucagon playing c r u c i a l r o l e s in the control of bowel glucose metabolism, oxygen consumption and heat p r oduction.…”

Section: Discussionmentioning

confidence: 95%

“…It is now clear, however, that in a thermo-neutral environment it accounts for at least 25% of the total heat production of the body (Grayson et al, 1971). Temperatures as high as 0.7°C above aortic may frequently be recorded from the lumen of the duodenum.…”

Section: Discussionmentioning

confidence: 99%

Effect of environment on temperatures in the viscera of the dog

Grayson

Durotoye²

1971

Int J Biometeorol

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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.

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“…In subsequent work it was shown that oxidative processes alone could not account for this level of heat production. There was a net uptake of glucose far in excess of that which could be accounted for on the basis of oxidative metabolism alone (Durotoye & Grayson, 1971).…”

Section: Introductionmentioning

confidence: 99%

The effect of catecholamines on intestinal glucose and oxygen uptake in the dog.

Grayson¹,

Oyebola²

1983

The Journal of Physiology

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SUMMARY1. Using the anaesthetized dog, continuous recording was made of the oxygen and glucose contents of the artery and the vein draining the upper jejunum. Flow was also measured and results expressed as differences in oxygen and glucose between the aorta and the jejunal vein (a-v), also as oxygen consumption and glucose uptake.2. Resting glucose uptake was greater than could be accounted for on the basis of oxidation.3. When adrenaline (1 ,tg/kg. min) or noradrenaline (2 ,sg/kg. min) was infused intravenously, oxygen uptake rose by about 50 % whereas glucose uptake rose by 300-500 %; moreover, the rise in glucose uptake was apparent before the rise in oxygen uptake.4. The f-blocking agent, propranolol (0-5 mg/kg. min) had no effect on oxygen uptake but caused a three-fold rise in glucose uptake. Subsequently infusion of adrenaline had no effect on oxygen uptake and no effect on glucose uptake. However, on stopping the infusion there was a marked drop in glucose uptake, which was not maintained.5. It is suggested that the effects of catecholamines may be due to altered arterial blood glucose levels and that the jejunum may play a role in glucose homeostasis which requires the action of fi receptors.

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Heat production in the gastro‐intestinal tract of the dog

Cited by 22 publications

References 5 publications

Effect of nicotine on blood flow, oxygen consumption and glucose uptake in the canine small intestine

Effect of nicotine on blood flow, oxygen consumption and glucose uptake in the canine small intestine

Effect of environment on temperatures in the viscera of the dog

The effect of catecholamines on intestinal glucose and oxygen uptake in the dog.

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