The purpose of the present study was to characterize, in vivo, the function and origin of peripheral alpha-adrenergic mechanisms in acral regions of the cutaneous microvasculature. Laser-Doppler flowmetry was used to continuously monitor changes in local @entity11924 ( @entity11924 ) measured at the plantar surface of the terminal phalange in the @entity35 . In @entity3652 -anesthetized @entity35 , the intravenous administration of @entity5521 (a nonselective alpha-adrenoceptor antagonist) elicited a dose-dependent (0.01-1.0 mg/kg, i.v.) increase in @entity11924 , a decrease in mean arterial pressure (MAP) and a marked reduction in cutaneous vascular resistance (CVR). These results demonstrate a high degree of endogenous alpha-adrenergic tone in the cutaneous microvasculature of the @entity35 . In pithed @entity35 , cutaneous vasoconstriction could be evoked by ganglionic stimulation with @entity6958 or by electrical stimulation of the peripheral cut end of the sciatic nerve trunk. @entity6958 and sciatic nerve responses were not altered by @entity1169 or @entity3897 , but were inhibited by @entity5521 . In addition, the effects of @entity6958 on @entity11924 were abolished by bilateral adrenal demedullation, but were unaltered by hindlimb denervation. These results suggest that the predominant vasoconstrictor tone in the cutaneous vasculature is mediated by a humoral action of circulating @entity2661 at postjunctional alpha-adrenoceptors. The adrenal medulla appears to be the origin of this humoral tone. Postganglionic sympathetic nerves play an insignificant role in mediating cutaneous vasoconstriction elicited by ganglionic stimulation.

Sympathetic regulation of cutaneous circulation in the XXXX .

@entity1169 :: ('MESH:D011433', 'Chemical') :: ['propranolol'] @entity5521 :: ('MESH:D010646', 'Chemical') :: ['phentolamine'] @entity3652 :: ('MESH:D007649', 'Chemical') :: ['ketamine'] @entity6958 :: ('MESH:D004246', 'Chemical') :: ['DMPP'] @entity11924 :: ('MESH:D017566', 'Disease') :: ['cutaneous microvascular perfusion', 'CP'] @entity3897 :: ('MESH:D001285', 'Chemical') :: ['atropine'] @entity35 :: ('10116', 'Species') :: ['rat', 'rats'] @entity2661 :: ('MESH:D002395', 'Chemical') :: ['catecholamines']
@entity35 :: (10116,Species) :: ['rat']
