Hepatic blood flow distribution: consideration of gravity, liver surface, and norepinephrine on regional heterogeneity.
Blood flow distribution within the livers of cats and dogs was assessed using 15-microns microspheres injected into the hepatic artery and portal vein. Representative vertical core samples (n = 11-18) were taken from the thickest part of each liver. Heterogeneity was assessed in several ways. The difference in total flow to different lobes was greater in dogs than in cats, and in dogs, those lobes with highest portal venous flow had lowest hepatic arterial flow. Overall flow variance was very high in both species, with adjacent surface samples in a single lobe showing variance of 15-22% for both vessels. The ratio of highest to lowest flow within core samples averaged 2.1-3.4 for both vessels in both species. The hepatic arterial flow was highest to the surface 2 mm of the liver. Portal flow most often (31% of all samples) showed a pattern of highest flow to the top, graduating down to lowest flow to the bottom (dorsal side) of the vertical cores. However, this pattern appeared much more frequently in the most ventral liver lobes and very seldom in the lobes lying beneath the liver mass. Norepinephrine reduced heterogeneity. Hepatic arterial occlusion for 10 min produced minor and inconsistent reduction of heterogeneity. Rotating cats from back to front and again to back disrupted patterns of distribution but not in a way that could be interpreted as due to effects of gravity. Flow patterns changed with time. The heterogeneity of perfusion appears to be under dynamic and multiple interacting forces.
Lautt
W W
WW
Department of Pharmacology and Therapeutics, Faculty of Medicine, University Manitoba, Winnipeg, Canada.
Schafer
J
J
Legare
D J
DJ
D000818:Animals; D002415:Cats; D004285:Dogs; D005260:Female; D006112:Gravitation; D006499:Hepatic Artery / Q000502:physiology; D008099:Liver / Q000033:anatomy & histology* / Q000098:blood supply; D008102:Liver Circulation / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008863:Microspheres; D009638:Norepinephrine / Q000494:pharmacology*; D010477:Perfusion; D010865:Pilot Projects; D011169:Portal Vein / Q000502:physiology; D013045:Species Specificity; D013997:Time Factors
D009638:Norepinephrine