Nitric oxide and cgmp do not affect fluid flux in isolated rat
lungs .
Eichinger, Mark R., and Benjimen R. Walker.
Department of Physiology, University of New Mexico, School of
Medicine, Albuquerque, NM 87131
APStracts 2:0368A, 1995.
We sought to examine the influence of NO and the second messengers
cGMP and intracellular calcium on fluid flux in lungs isolated from
male Sprague Dawley rats perfused with saline (containing 4% albumin)
or with whole blood. Lungs were allowed to equilibrate for a period
of 30 min without treatment (controls), or with one of the following
agents: the exogenous NO donor spermine NONOate, the nitric oxide
synthase inhibitor N_-nitro-L-arginine (L-NNA;), 8-bromo cGMP, the
calcium ionophore ionomycin, or the endothelial injurious agent
protamine. Following equilibration, perfusate reservoir height was
increased to five incremental settings to increase pulmonary venous
pressure and enhance fluid flux. Perfusate reservoir weight was
monitored continuously as an index of fluid flux. Lung wet/dry weight
was determined upon completion of the experiments. Increasing
reservoir height was associated with an increase in pulmonary
arterial, pulmonary capillary and pulmonary venous pressures, and an
increase in fluid flux. However, treatment with exogenous NO or
inhibition of endogenous NO was without effect on fluid flux in
saline lungs at two different flow rates or in whole blood perfused
lungs. Similarly, treatment with cGMP and ionomycin did not alter
fluid flux. Protamine pretreatment resulted in a significant increase
in fluid flux at the highest reservoir setting, although exogenous NO
and L-NNA pretreatments were without further effect on the protamine
treated lungs. Thus, a role for NO and the second messengers cGMP and
Ca2+ in modulating fluid flux could not be demonstrated in the
isolated rat lung.
Received 3 March 1995; accepted in final form 16 August 1995.
APS Manuscript Number A237-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 24 August 1995.