MECHANISMS IN THE PRESSOR EFFECTS OF HEPATIC PORTAL VENOUS FATTY-ACIDINFUSION

Mechanisms in the presser effects of hepatic portal venous fatty acid infusion. Am. J. Physiol. 273 (Regulatory Integrative Comp. Physiol. 4 2): E2324-R330, 1997.-Portal venous infusion of oleate solution has pr esser effects. We have examined efferent mechanisms, measured the resp onse to sustained infusion, and determined the effect of linoleate. Ei ght conscious animals received concurrent infusions of prazosin or veh icle with portal venous infusion of oleate. Oleate alone increased mea n arterial pressure from 109.0 +/- 4.1 to 123.0 +/- 5.8 mmHg (P = 0.02 ), whereas no increase in blood pressure occurred when oleate was infu sed with prazosin. In 10 rats, concurrent infusion of losartan had no effect on the presser activity of portal oleate infusion. Twenty-two a nimals received portal oleate or vehicle as a continuous infusion far 7 days. Mean arterial pressure (126.1 +/- 2.0 vs. 107.8 +/- 2.6 mmHg, P < 0.001) and heart rate (383 +/- 5 vs. 366 +/- 5, P = 0.0257) were i ncreased in oleate-infused animals. No differences in plasma fatty aci ds, glucose, insulin, presser hormones, liver enzymes, or in vitro art erial presser responsiveness were observed. Portal venous infusion of linoleate increased arterial pressure by 12.2 +/- 3.2 mmHg (P = 0.033) . These results indicate that alpha-adrenergic activity is necessary f or the acute presser effects of portal oleate, that sustained portal o leate infusion results in persistent blood pressure elevation, and tha t other long-chain fatty acids besides oleate have presser effects.