Journal of Applied Physiology, Vol 67, Issue 2 833-838, Copyright © 1989 by American Physiological Society
Sinoaortic deafferentation reduces intrapulmonary shunt in dogs with oleic acid lung injury
M. Leeman, J. Closset, J. L. Vachiery, P. Lejeune, C. Melot and R. Naeije
Laboratory of Cardiovascular and Respiratory Physiology, Erasme University Hospital, Brussels, Belgium.
Hypoxic stimulation of the peripheral chemoreceptors has been reported to
inhibit hypoxic pulmonary vasoconstriction. To evaluate the
pathophysiological importance of this observation, we investigated the
effects of surgical peripheral chemoreceptor denervation on pulmonary
vascular tone and gas exchange in 17 pentobarbital-anesthetized dogs with
oleic acid pulmonary edema. Pulmonary arterial pressure-cardiac index
(Ppa/Q) plots, blood gases, and intrapulmonary shunt measured by the SF6
method were obtained at base line, after peripheral chemodenervation (n =
9) or after sham operation (n = 8), and again after 0.09 ml.kg-1
intravenous oleic acid. Over the range of Q studied (2-5 l.min-1.m-2),
Ppa/Q plots were best fitted as first-order polynomials in most dogs in all
experimental conditions. Chemoreceptor denervation increased Ppa at the
lowest Q, while sham operation did not affect the Ppa/Q plots. Oleic acid
increased Ppa over the entire range of Q and increased intrapulmonary
shunt. This latter was measured at identical Q during the construction of
the Ppa/Q plots. Chemoreceptor-denervated dogs, compared with sham-operated
dogs, had the same pulmonary hypertension but lower intrapulmonary shunt
(36 +/- 4 vs. 48 +/- 5%, means +/- SE, P less than 0.04) and venous
admixture (43 +/- 4 vs. 54 +/- 3%, P less than 0.02). We conclude that in
intact dogs chemoreceptor denervation attenuates the rise in intrapulmonary
shunt after oleic acid lung injury. Whether this improvement in gas
exchange is related to an enhanced hypoxic pulmonary vasoconstriction is
uncertain.
