Comparison of the effects of prostaglandins A, E, F, and B on the canine pulmonary vascular bed.

The present data show that prostaglandins of the A, E, F, and B series have a wide spectrum of effects on the canine pulmonary vascular bed. PGF2alpha and PGB2 were very potent pulmonary pressor substances. Both of these agents increased pressure in the lobar artery and small vein. Since blood flow was constant and left atrial pressure did not rise, the increase in lobar arterial pressure reflects an increase in resistance to flow in the lung. The rise in venous pressure and the increase in pressure gradient between lobar artery and vein indicate that these substances increase pulmonary vascular resistance by constricting lobar veins and upstream vessels presumed to be small arteries. PGE1 and PGA1 both dilated the pulmonary vascular bed and the decrease in resistance was due to dilation of veins and upstream vessels. In the dog, both PGE2 and PGA2 were found to be modest pulmonary pressor substances. The increase in resistance with both agents was similar in blood and dextran-perfused lung lobes, hence interaction with formed elements contribute little, if anything, to these responses.