Hypoxic vasoconstriction in pulmonary arterioles and venules.
Hillier, Simon C., Jacquelyn A. Graham, Christopher C. Hanger,
Patricia S. Godbey, Robb W. Glenny, and Wiltz W. Wagner, Jr.
Departments of Anesthesia, Physiology/Biophysics, and Pediatrics,
Indiana University School of Medicine, Indianapolis, IN 46202, and
Departments of Medicine and of Physiology and Biophysics, University
of Washington, Seattle, WA 98195
APStracts 3:0542A, 1996.
Pulmonary microvessels (<70 [mu]m) lack a complete muscular media.
We tested the hypothesis that these thin walled vessels do not
participate in the hypoxic pressor response. Isolated canine lobes
were pump perfused at precisely known microvascular pressures. A
videomicroscope, coupled to a computerized image enhancement system,
permitted accurate diameter measurements of subpleural arterioles and
venules, each vessel serving as its own control. While maintaining
vascular pressure constant throughout the protocol, hypoxia caused an
average reduction of 25% of microvessel diameters. The constriction
was reversed when nitric oxide was added to the hypoxic gas mixture.
The nitric oxide reversal, combined with a lack of lobar blood flow
redistribution as measured by fluorescent microspheres, shows that
the constriction was active. This response suggests the unexpected
potential for active intra-acinar ventilation-perfusion matching.
Received 22 February 1996; accepted in final form 15 November
1996.
APS Manuscript Number A175-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996