Prostacyclin, thromboxane, and prostaglandin F2 alpha in maternal plasma during breast-feeding.

In order to study the role of prostaglandin F2 alpha (PGF2 alpha) prostacyclin (PGI2), and thromboxane A2 in milk ejection, the stable metabolites of these prostanoids, i.e., 13,14-dihydro-15-keto-PGF2 alpha (M-PGF2 alpha), 6-keto-PGF1 alpha, and thromboxane B2, respectively, were measured from serial samples of plasma collected from 11 puerperal women before, during, and after breast-feeding. The plasma M-PGF2 alpha decreased significantly (p less than 0.01) from the level of 253.6 +/- 18.6 pg/ml (mean +/- SE) before suckling to 204.2 +/- 26.1 pg/ml at the end of suckling, but returned to 234.6 +/- 26.1 pg/ml 60 minutes after the end of suckling. The 6-keto-PGF1 alpha concentration also decreased (p less than 0.01) from 246.4 +/- 30.9 to 187.9 +/- 9.9 pg/ml within the first 15 minutes of suckling, whereas the thromboxane B2 levels did not change. Thus, these results suggest that PGF2 alpha and PGI2 are involved with milk ejection and lactation in human beings.