Changes in expression of P2X1 receptors and connexin 43 in the rat myometriurn during pregnancy

Objective: To investigate the expression of P2X(1) receptors and connexin 43 in gap junctions between smooth muscle cells. Contraction mediated by P2X receptors is known to occur in the bladder and male reproductive tract, and cell-cell coupling of smooth muscle via gap junctions is essential for synchronized rhythmic activity of these tissues. Design: We selected for this study rat myrometrial smooth muscle during pregnancy and at postpartum day 1. Setting: University medical school. Animal(s): Laboratory rats. Intervention(s): Rats were mated and became pregnant. Main Outcome Measure(s): Immunostaining and fluorescence and confocal microscopy. Result(s): The level of P2X1 receptor expression remained low throughout pregnancy (days 4 to 20) but was greatly up-regulated at day 22 (postpartum day 1). Connexin 43 expression showed a pattern of up-regulation, with progression through pregnancy and peaking near labor, but exhibited a rapid down-regulation after parturition. Conclusion(S): The functional significance of the changes in connexin 43 and P2X(1) receptor expression that have been observed is discussed in relation to triggering and modulation of uterine contractility during and after pregnancy. (Fertil Steril (R) 2007;88(Suppl 2):1174-9. (C)2007 by American Society for Reproductive Medicine.)