RT Journal Article
SR Electronic
T1 Alpha adrenoceptor subtype mediating sympathetic mobilization of blood from the hepatic venous system in anesthetized cats.
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 224
OP 229
VO 236
IS 1
A1 R Segstro
A1 C Greenway
YR 1986
UL http://jpet.aspetjournals.org/content/236/1/224.abstract
AB Previous studies have suggested that sympathetic effects on hepatic blood volume may be mediated through alpha-2 adrenoceptors in anesthetized cats as prazosin did not block whereas phentolamine and phenoxybenzamine impaired these responses markedly. In this study we have shown that yohimbine blocks hepatic volume responses to both nerve stimulation and norepinephrine infusions. In comparison with norepinephrine, phenylephrine had much weaker effects on hepatic blood volume than on arterial and portal pressures. Clonidine produced a slow weak contraction of the hepatic venous bed which was blocked by yohimbine but not by prazosin. alpha-Methylnorepinephrine produced a norepinephrine-like contraction of the hepatic venous bed which was blocked by yohimbine but not by prazosin. Taken together, these data suggest that hepatic blood volume responses to both sympathetic nerve stimulation and infusions of catecholamines are mediated through alpha-2 adrenoceptors, whereas portal pressure responses are mediated through both alpha-1 and alpha-2 adrenoceptors.