Phosphodiesterase 5 inhibition restores impaired ACh relaxation in hypertensive
conduit pulmonary arteries.
Oka, Masahiko.
Department of Respiratory Medicine, Juntendo University School of Medicine,
Tokyo 113«hyphen»8421, Japan
APStracts 7:0265L, 2000.
Responses to acetylcholine (ACh) and sodium nitroprusside (SNP) were compared in
large (LPA) and small pulmonary artery (SPA) rings from normoxic (N) and chronically
hypoxic (CH) rats. In addition, the effects of a selective phosphodiesterase (PDE) 5
inhibitor E-4021 on ACh-induced relaxation were evaluated. Chronic hypoxia markedly
decreased both ACh- and SNP-induced relaxations in LPA but not in SPA. Pretreatment
with E-4021 caused a much greater leftward shift of the concentration-response curve for
ACh in hypoxic than in normoxic LPA, eliminating the difference in response to ACh
between these two vessels. These results suggest that cGMP-dependent relaxation is
impaired in the proximal but not distal pulmonary artery of CH rats and that increased
PDE5 activity could be a mechanism responsible for this impaired responsiveness.
Received 10 August 2000; accepted in final form 28 September 2000
APS Manuscript Number L288-0.
Article publication pending Am J Physiol Lung Cell Mol Physiol
ISSN 1080-4757 Copyright 2000 The American Physiological Society.
Published in APStracts on 30 November 2000