Forearm vasodilator mechanisms during mental stress- possible roles
of epinephrine and anp.
Lindqvist, Madeleine, Thomas Kahan, Anders Melcher, Peter Bie, and
Paul Hjemdah.
Karolinska Institute, Division of Clinical Physiology, Danderyd
Hospital, Danderyd, Sweden, Karolinska Institute, Division of
Internal Medicine, Danderyd Hospital, Danderyd, Sweden, Dept. of
Clinical Pharmacology, Karolinska Hospital, Stockholm,Sweden, Dept.
of Physiology, Panum Institute, University of Copenhagen, Copenhagen,
Denmark
APStracts 2:0216E, 1995.
The contribution of epinephrine (Epi) to forearm vasodilator responses
to mental stress was evaluated in 12 healthy men by comparing
hemodynamic and plasma catecholamine responses to mental stress and
to intravenous and intraarterial infusions of epinephrine. Mental
stress decreased forearm vascular resistance (FVR) by 45 %; increased
arterial Epi from 0.23 to 0.44 nmol/L in arterial plasma and
increased forearm norepinephrine overflow. Intraarterial Epi infusion
decreased FVR concentration-dependently by up to 43 %. Intravenous
Epi infusion decreased diastolic arterial pressure and increased
heart rate and systolic blood pressure dose-dependently. FVR
decreased by up to 39 % at 4.60 nmol/L Epi in arterial plasma. The
average Epi contribution to forearm vasodilatation during mental
stress was calculated to be between 9 and 30 %, depending on if
responses to stress were compared to intravenous or intraarterial Epi
infusion. Arterial atrial natriuretic peptide immunoreactivity
increased by 23 % during stress, supporting a vasodilator influence,
whereas vasopressin immunoreactivity was unaffected. Thus, secretion
of Epi explains only part of the stress-induced forearm
vasodilatation. Intravenous infusion of Epi appears to activate
sympathetic counterregulation.
Received 29 June 1995; accepted in final form 12 October 1995.
APS Manuscript Number E301-5.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95