Lack of liver vascular response to carotid occlusion in mildly acidotic dogs

Abstract

The effect of mild acidosis on the reduction in liver vascular volume provoked by reflex sympathetic activation was ascertained in dogs by use of the multiple indicator-dilution technique. Portal vein-hepatic vein dilution patterns were obtained following injection of a mixture containing 51Cr-labeled red blood cells (a vascular reference), 14C-labeled sucrose (an interstitial reference), and 3H-labeled water (a cellular reference). Liver vascular, interstitial, and cellular water spaces were measured in normal and mildly acidotic dogs under basal conditions and during bilateral carotid artery occlusion. Carotid occlusion resulted in a large increase in arterial blood pressure in normal and a lesser increase in acidotic dogs, but the increase in portal and hepatic vein norepinephrine and decrease in liver vascular and interstitial volumes observed in normal dogs did not occur in the acidotic animals; no change in labeled water accessible liver cellular spaces was perceptible. The data indicate that mild acidosis abolishes the ordinarily expected reduction in liver vascular volumes on sympathetic activation in the intact dog but not the arterial pressor response.