Gastrointestinal and mesenteric hemodynamic patterns in neurogenic hypertensive rabbits.

Abstract

Patterns of blood flow and vascular resistance in the component tissues of the splanchnic region of sinoaortic denervated (SAD) hypertensive rabbits were compared with those of normotensive sham-operated rabbits using previously described methods. SAD rabbits with high total splanchnic resistance showed significant elevations in resistance in all parts of the gastrointestinal tract and mesentery, but the magnitude of the changes compared with values for sham-operated rabbits varied from one area to another, ranging from increases of 34% in the cecum-appendix to 77% in the stomach and jejunum. Blood flow was reduced 22-42% in some areas and less in others. An aboral gradient of mean blood flow was found between and within the small and large intestines in both groups. Intestinal flow pattern differences were found in individual rabbits. We concluded that activation of the sympathetic nervous system by sinoaortic denervation exerted a variable, unpredictable degree of vasoconstrictor tone on different parts of the splanchnic bed which reflected the net result of vascular smooth muscle response to neurogenic and local regulatory factors.