Journal of Applied Physiology, Vol 55, Issue 2 558-561, Copyright © 1983 by American Physiological Society
Low exercise pulmonary resistance is not dependent on vasodilator prostaglandins
J. Lindenfeld, J. T. Reeves and L. D. Horwitz
In resting conscious dogs, administration of cyclooxygenase inhibitors
results in modest increases in pulmonary arterial pressure and pulmonary
vascular resistance, suggesting that vasodilator prostaglandins play a role
in maintaining the low vascular resistance in the pulmonary bed. To assess
the role of these vasodilator prostaglandins on pulmonary vascular
resistance during exercise, we studied seven mongrel dogs at rest and
during exercise before and after intravenous meclofenamate (5 mg/kg).
Following meclofenamate, pulmonary vascular resistance rose both at rest
(250 24 vs. 300 +/- 27 dyn . s . cm-5, P less than 0.01) and with exercise
(190 +/- 9 vs. 210 +/- 12 dyn . s . cm-5, P less than 0.05). Systemic
vascular resistance rose slightly following meclofenamate both at rest and
during exercise. There were no changes in cardiac output. The effects of
cyclooxygenase inhibition, although significant, were less during exercise
than at rest. This suggests that the normal fall in pulmonary vascular
resistance during exercise depends largely on factors other than
vasodilator prostaglandins.
