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ADRENERGIC MECHANISMS IN THE HEPATIC MICROCIRCULATION IN THE RAT
Author(s) -
Koo Anthony,
Liang Isabella Y. S.,
Cheng K. K.
Publication year - 1977
Publication title -
quarterly journal of experimental physiology and cognate medical sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0033-5541
DOI - 10.1113/expphysiol.1977.sp002392
Subject(s) - microcirculation , adrenergic , medicine , receptor
The in vivo hepatic microvascular bed of the rat was observed microscopically in the transilluminated liver and the diameter of the hepatic sinusoids was measured by serial photomicrography. Intraportal infusion of tyramine induced concentration‐dependent constriction of the hepatic sinusoids, but also dilatation of the sinusoids when the dose was small. These effects were attributed to the release of endogenous noradrenaline which activated either alpha‐ or beta‐adrenergic receptors and caused constriction, or dilatation, of the sinusoids respectively. Adrenaline and noradrenaline induced similar changes in the hepatic sinusoids as tyramine, while phenoxybenzamine induced dilatation, and propranolol constriction, of the sinusoids. All the above responses were abolished by pretreatment with reserpine. A possible noradrenaline‐mediated basal vasomotor tone in the hepatic sinusoids for autonomic control of the blood flow in the sinusoids was postulated.