Effects of acute, passive hepatic congestion on blood flow and oxygen uptake in the intact liver of the cat.

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Abstract
Raising the hepatic venous pressure experimentally duplicates the type of hepatic congestion seen in many clinical situations including congestive heart failure. Venous pressure was controlled using a hepatic venous long circuit preparation and was raised by 6 cm blood (4.7 mm Hg) or 10 cm (7.8 mm Hg). Total splanchnic blood flow and oxygen uptake were reduced by these maneuvers but hepatic arterial flow was not altered nor was hepatic oxygen uptake. Blood flow in the portal vein decreased to 65 +/- 12% of control and gut oxygen uptake decreased to 60 +/- 14% of control. The data confirm that raised hepatic venous pressure does not produce hepatic edema in spite of massive prolonged fluid filtration across the liver into the peritoneum. In spite of a reduced (to 84 +/- 3% of control) hepatic oxygen delivery, the liver can maintain oxygen uptake (99 +/- 7% of control) by increasing oxygen extraction to appropriate levels. The hepatic artery in these cats were capable of myogenic vasoconstriction in response to altered arterial pressure, but in response to raised venous pressure no tendency for constriction was seen. This is in marked contrast to the vasoconstriction seen in isolated perfused livers where portal blood flow is held constant during the raised venous pressure.