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COMPARATIVE AND EVOLUTIONARY PHYSIOLOGY

Effects of gastric distension on the cardiovascular system in rainbow trout (Oncorhynchus mykiss)

Department of Zoology, Göteborg University, Gothenburg, Sweden

Submitted 17 December 2007 ; accepted in final form 10 March 2008

When animals feed, blood flow to the gastrointestinal tract increases to ensure an adequate oxygen supply to the gastrointestinal tissue and an effective absorption of nutrients. In mammals, this increase depends on the chemical properties of the food, as well as, to some extent, on the mechanical distension of the stomach wall. By using an inflatable nitrile balloon positioned in the stomach, we investigated the cardiovascular responses to mechanical stretch of the stomach wall in rainbow trout (Oncorhynchus mykiss). Distension with a volume equivalent to a meal of 2% of the body mass increased dorsal aortic blood pressure by up to 29%, and central venous blood pressure increased transiently nearly fivefold. The increase in arterial pressure was mediated by an increased vascular resistance of both the systemic and the intestinal circulation. Cardiac output, heart rate, and stroke volume (SV) did not change, and only transient changes in gut blood flow were observed. The increase in arterial pressure was abolished by the -adrenergic antagonist prazosin, indicating an active adrenergic vasoconstriction, whereas the venous pressor response could be the consequence of a passive increase in intraperitoneal pressure. Our results show that mechanical distension of the stomach causes an instantaneous increase in general vascular resistance, which may facilitate a redistribution of blood to the gastrointestinal tract when chemical stimuli from a meal induce vasodilation in the gut circulation. The normal postprandial increase in gut blood flow in teleosts is, therefore, most likely partly dependent on mechanical stimuli, as well as on chemical stimuli.

blood flow; coeliacomesenteric artery; postprandial; mechanical stimuli; teleost

This article has been cited by other articles:

				A. Grans, F. Albertsson, M. Axelsson, and C. Olsson Postprandial changes in enteric electrical activity and gut blood flow in rainbow trout (Oncorhynchus mykiss) acclimated to different temperatures J. Exp. Biol., August 15, 2009; 212(16): 2550 - 2557. [Abstract] [Full Text] [PDF]

				H. Seth, E. Sandblom, and M. Axelsson Nutrient-induced gastrointestinal hyperemia and specific dynamic action in rainbow trout (Oncorhynchus mykiss)--importance of proteins and lipids Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2009; 296(2): R345 - R352. [Abstract] [Full Text] [PDF]

				H. Seth and M. Axelsson Effects of gastric distension and feeding on cardiovascular variables in the shorthorn sculpin (Myoxocephalus scorpius) Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2009; 296(1): R171 - R177. [Abstract] [Full Text] [PDF]