AJP - Heart and Circulatory Physiology, Vol 259, Issue 1 93-100, Copyright © 1990 by American Physiological Society

ARTICLES

Inhibition of hypoxic pulmonary vasoconstriction by increased left atrial pressure in dogs

P. Lejeune, J. M. De Smet, P. de Francquen, M. Leeman, S. Brimioulle, R. Hallemans, C. Melot and R. Naeije
Laboratory of Cardiovascular and Respiratory Physiology, Erasme University Hospital, Brussels, Belgium.

To further explore the mechanism of hypoxic pulmonary vasoconstriction, we studied the mean pulmonary arterial pressure (Ppa)/left atrial pressure (Pla) relationship at fixed cardiac index (Q) and the Ppa/Q relationship at several levels of fixed Pla in pentobarbital sodium-anesthetized dogs ventilated alternately in hyperoxia [fraction of inspired O2 (FIO2) 0.4 or 1.0] and in hypoxia (FIO2 0.1). In all experimental conditions, Ppa/Q plots were linear with extrapolated pressure intercepts (Pi) not significantly different from Pla. Hypoxia increased the slope of Ppa/Q plots and did not affect Pi. In hyperoxia, increasing Pla (3 to 26 mmHg) induced approximately equal increases in Ppa at fixed Q and shifted Ppa/Q plots toward higher pressures in a parallel manner. In hypoxia, increasing Pla (4 to 25 mmHg) did not affect Ppa at fixed Q until Pla exceeded 16 mmHg and shifted Ppa/Q plots toward higher pressures with a decrease in slope. Consequently, the hypoxia-induced increases in Ppa at constant Q and constant Pla were attenuated at higher Pla. Thus, in anesthetized dogs, hypoxia increases the slope of Ppa/Q plots without affecting Pi at fixed Pla, and an increase in Pla inhibits hypoxic pulmonary vasoconstriction. These results can be explained without invoking a hypoxia-induced Starling resistor mechanism in the pulmonary circulation.

This article has been cited by other articles:

				F. Kerbaul, C. Guidon, J. Stephanazzi, M. Bellezza, P. Le Dantec, T. Longeon, and M. Aubert Sub-MAC concentrations of desflurane do not inhibit hypoxic pulmonary vasoconstriction in anesthetized piglets : [La vasoconstriction pulmonaire hypoxique n'est pas inhibee par des concentrations de desflurane inferieures a la CAM chez des porcelets anesthesies] Can J Anesth, September 1, 2001; 48(8): 760 - 767. [Abstract] [Full Text] [PDF]

				F. Kerbaul, M. Bellezza, C. Guidon, L. Roussel, M. Imbert, J. P. Carpentier, and J. P. Auffray Effects of sevoflurane on hypoxic pulmonary vasoconstriction in anaesthetized piglets Br. J. Anaesth., September 1, 2000; 85(3): 440 - 445. [Abstract] [Full Text] [PDF]