Expression of protein kinase C isozymes in nonpregnant and pregnant human myometrium

OBJECTIVE: The aim of this study was to compare the distributions of protei n kinase C isozymes in human nonpregnant and pregnant myometrial tissues an d primary cell cultures. STUDY DESIGN: Myometrial tissues were obtained at hysterectomy from nonpreg nant women and at cesarean delivery from women both before and during early labor at term. Western immunoblot analysis was performed on homogenates of myometrial tissues and primary cell cultures with monoclonal antibodies sp ecific for protein kinase C isozymes. Redistribution and translocation of p rotein kinase C were examined by means of immunocytochemical methods. RESULTS: Nonpregnant myometrial tissues contained protein kinase C isozymes alpha, gamma, delta, mu, iota, and zeta but not beta (1), beta (2), theta, or epsilon. Pregnant myometrial tissues both before and during early labor contained the same protein kinase C isozymes and also beta (1) and beta (2 ). The protein kinase C isozyme distribution in primary myometrial cell cul tures was identical to that in the myometrial tissues. Protein kinase C red istribution and translocation were demonstrated in these cultured myometria l cells. CONCLUSION: Both human myometrial tissues and primary cell cultures express ed a broad range of protein kinase C isozymes. Protein kinase C isozymes pi and Pa were absent in nonpregnant myometrium but were induced during pregn ancy. Labor at term did not alter protein kinase C isozyme expression.