Hepatic arteries in normotensive and spontaneously hypertensive rats. A morphometric study

The media thickness (m), luminal radius (r) and m/r ratio were determined in the hepatic arterial trunk and in intra-hepatic arterial branches as was the number of arteries per cm2 sectioned liver tissue in spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto controls (WKY). The cross-sectional vessel parameters were calculated for a standardized condition, in which the internal elastic membrane is smooth and circular. Both intra-hepatic arterial branches and the hepatic arterial trunk showed significantly higher m/r ratios in SHR than in WKY controls. The luminal radius of the hepatic arterial trunk was larger in SHR than in WKY (P less than 0.05). The number of arteries per cm2 sectioned liver tissue was greater in SHR (P less than 0.05). It is suggested that the consequences of the increased m/r ratio in hepatic arteries of SHR are counteracted to some extent by an increased vascularization, but that during hypovolaemia and compensatory vasoconstriction, a greater decrease in hepatic arterial blood flow occurs in SHR than in WKY.