Modulation by estradiol of rabbit atrial chronotropic response to histamine.

The chronotropic response (Δ rate) to histamine of atria from estradiol 17-β (E; 0.1 mg/kg)-treated (14 days) rabbit was significantly greater compared to those from control rabbits. However, the maximum response of atria from rabbits treated with a higher dose of E (1.0 mg/kg) was not significantly different from control. Cimetidine (2.8×10 M) inhibited the theoretical maximum increase in rate to histamine in all 3 groups, control 25%, E (0.1 mg) 42% and E (1.0 mg) 35%. [ABSTRACT FROM AUTHOR]