Effects Of Estradial Combined With Progesterone On Action Potential In Rabbit Sino-Atrial Node Cells

Objective: To investigate the effects of estradiol combined with progesterone on action potential(AP) of rabbit sino-atrial node and to find the optimum dose on combined use. Methods: Using conventions glass microelectrode technique .The task included two parts: 1)adopting L/32(49) orthogonal design arrayed experiments and analyzed results. (2)We observed the effects of E2 combined with P on the response of SA node cells to high Ca2+(5mmol/L). Results: 1) E2 or P prolonded AP duration (APD20, APD50, APD90 and APD), RPT and DPT, slowed down the maximal rate of rise of phase 0(Vmax), decreased the action potential amplitude(APA). 2)There are interactive action between E2 and P, P can strengthen E2 in some degree. The optimum dose on combined use is E2P2(E2 combined with P in low doses). 3) E2P2 antagonized the effects of high Ca2+ on SA node cells. Conclusion:The results suggested that E2 or P maybe inhibit the K+ channels and the Ca+ channels. The combinations of E2 and P in clinical aplication should be low doses.