15-Methylation augments the cardiovascular effects of prostaglandin F-2alpha

Intramuscular injection of the 15-methyl analogue of prostaglandin F-2alpha (15-ME-PGF-2alpha) is being used to initiate second trimester abortion. The natural prostaglandin F-2alpha (PGF-2alpha) is a known pulmonary pressor agent but there is little information about the cardiovascular effects of the analogue. Consequently, we compared the hemodynamic responses to the two forms in twenty-three anesthetized dogs. Given I.M. or I.V. 15-me-PGF-2alpha produced a greater and more sustained rise in pulmonary arterial pressure than PGF-2alpha. Intramuscular 15-me-PGF-2alpha also elicited a more prolonged increase in pulmonary vascular resistance than prostaglandin F-2alpha given I.M. or I.V. The methyl analogue (I.M. or I.V.) causes a greater initial fall in systemic arterial oxygen tension and cardiac output, and a greater increase in systemic resistance than I.M. PGF-2alpha. Breathlessness seen during abortion induced by prostaglandin F-2alpha or its methyl analogue may be caused by acute pulmonary hypertension in addition to bronchoconstriction.