Decreased endometrial blood flow and plasma progesterone level after instillation of 10 μg prostaglandin F 2α into the lumen of the uteri of rhesus monkeys

Abstract

Instillations of 10 μg prostaglandin F 2α were performed once a week for four weeks into the lumina of the uteri of three nonsedated rhesus monkeys. Before and immediately after the instillation the endometrial blood flow was measured with the 133Xenon clearance technique. Plasma progesterone was measured by a radioimmunoassay method in blood samples taken before and 20 hrs after the instillation. The results showed a significant (p = 0.01) decrease to 39% (mean) of the original blood flow and a decrease to 23% (mean) of the original plasma progesterone content. The results also indicated a conditioning of the monkeys, causing a decreased endometrial blood flow, to the prostaglandin treatment from the third week on. The decrease of the endometrial blood flow may be caused by a local PG 2α-induced vasoconstriction. The decrease in plasma progesterone may be a direct luteolytic effect of prostaglandin F 2α, or it may be caused by a uterine factor, the secretion of which is stimulated by the relative ischaemia lasting at least 15 mins.