Pulmonary vasodilator drugs decrease lung liquid production in fetal sheep. Cummings, James J. Department of Pediatrics, State University of New York at Buffalo, 14222
APStracts 2:0233A, 1995.
To examine a potential relationship between pulmonary vasodilatation and fetal lung liquid production, I measured lung liquid production in 20 fetal sheep at 130 +/- 4 d gestation while using several agents known to increase pulmonary blood flow. Thirty-two studies were done in which left pulmonary arterial flow (QLPA) was measured by an ultrasonic doppler flow probe and net lung luminal liquid production (JV) was measured by plotting the change in lung luminal liquid concentration of radiolabelled albumin, an impermeant tracer that was mixed into the lung liquid at the start of each study. QLPA and JV were measured during a 1-2 hour baseline period and then during a 1-2 hour infusion period in which the fetuses received either an iv infusion of acetylcholine (n=8), prostaglandin D2 (n=10), or the leukotriene blocker FPL-55712 (n=7). These vasodilators work by different mechanisms, each mechanism having been implicated in the decrease in pulmonary vascular resistance seen at birth. Control (saline) infusions (n=7) caused no change in either QLPA or JV over 4 hours. All vasodilator agents significantly increased pulmonary blood flow and decreased net lung liquid production. Pulmonary arterial pressure did not change significantly in either the control, acetylcholine, prostaglandin, or leukotriene blocker studies indicating that pulmonary vascular resistance decreased. Thus, agents which increase pulmonary blood flow by mechanisms that occur at birth also decrease lung liquid production in fetal lambs. 

Received 21 November 1994; accepted in final form 25 May 1995.
APS Manuscript Number A1186-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on  8 June 1995.