Effect of calcium channel blockers long-term use on blood level of luteinizing hormone and estradiol in rats
Aim. To define the effect of calcium channel blockers long-term use on blood level of luteinizing hormone and estradiol in female rats. Methods. 82 mature female outbreed rats were distributed to seven groups. The rats of the first (control) group were administered 0.2 ml of 0.9% saline intraperitoneally for 21 day. Instead of saline, 5 and 25 mg/kg of verapamil were used in rats of the second and third groups, 5 and 10 mg/kg of nifedipine - in rats of the 4th and 5th groups, 5 and 20 mg/kg of diltiazem - in rats of the 6th and 7th groups accordingly. Blood levels of luteinizing hormone and estradiol were determined by ELISA after animals were withdrawn from the study. Results. In rats treated with calcium channel blockers, a dose-dependent decrease of luteinizing hormone and estradiol blood levels were observed. High doses of verapamil (group 3) decreased the level of luteinizing hormones and estradiol by 50% compared to control group, high doses of diltiazem (group 7) - by 50%. Only minor changes were observed in rats who were administered nifedipine, even in high doses. Conclusion. Observed decrease of blood estradiol level indicate the influence of calcium channel blockers directly on ovarian function; decrease of blood luteinizing hormone level might by secondary due to positive feedback between the estradiol and luteinizing hormone secretion and reflect decreased estradiol blood level.