Role of Protein Kinase C alpha in Regulation of [Ca2+](I) and Force in Human Myometrium

Recent findings implicate protein kinase C in regulation of contraction of uterine muscle (myometrium). However, the role of protein kinase C isoforms in myometrial contraction remains uncertain. Therefore, this study examined protein kinase C alpha's role in regulation of contraction and intracellular calcium concentration ([Ca2+](I)) of myometrium from term pregnant women. The authors demonstrated that protein kinase C alpha inhibitor Go6976 decreased the amplitude of potassium chloride-induced myometrial contractions in a time-dependent manner. The treatment of the myometrial strips with protein kinase C alpha-specific antisense oligodeoxynucleotides decreased the potassium chloride-induced contraction and [Ca2+](I) response to 39.3% +/- 6.8% and 50% +/- 3.3%, respectively, compared to control. The sense oligonucleotides treatment did not significantly change the potassium chloride responses (89.8% +/- 6.8% and 93.9% +/- 4.5% of the control for the contraction and [Ca2+](I), respectively). These data, coupled with the observation that protein kinase C alpha levels are elevated in the pregnant myometrium, suggest the involvement of protein kinase C alpha in regulation of human uterine contraction.