Arteriolar responses to extracellular atp in striated muscle.
McCullough, William T., Diane M. Collins, and Mary L. Ellsworth.
Department of Pharmacological and Physiological Science, Saint
Louis University Health Sciences Center, School of Medicine, St.
Louis, MO 63104, USA
APStracts 3:0522H, 1996.
Blood flow and its distribution must be appropriately regulated to
ensure that perfusion is matched to local tissue demands. We
investigated the role of ATP in triggering a conducted alteration in
arteriolar diameter in the Saran-covered, cheek pouch retractor
muscle of anesthetized hamsters (n=60). Vascular responses were
observed using in vivo video microscopy upstream from the site of
micropressure application of ATP (10-8 - 10-4M) either into the lumen
or just outside the wall of 1o and 2o arterioles. The role of nitric
oxide (NO) in the vascular responses to ATP was determined by
inhibiting NO synthase activity with N_-nitro-L-arginine methyl ester
(L-NAME) with and without co-administration of an excess of L
-arginine. Intraluminal application of ATP lead to a concentration
-dependent vasodilation which was conducted upstream along the
arteriole. The dilatory response was blocked by systemic pretreatment
with L-NAME and was maintained in the presence of an excess of L
-arginine. In contrast, ATP introduced extraluminally resulted in a
conducted vasoconstrictor response which was enhanced by pretreatment
with L-NAME. The dilator response to intraluminal ATP, in the context
of ATP release from erythrocytes under conditions associated with
decreased supply relative to demand, supports a role for the
erythrocyte in communicating local tissue needs to the vasculature
enabling the appropriate matching of oxygen supply to demand.
Received 29 May 1996; accepted in final form 1 November 1996.
APS Manuscript Number H479-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996