Pretreatment of male guinea pigs by 17-beta-estradiol induces hypersensitivity of beta-adrenoceptors in electrically driven left atria.

Background: It is well known that estrogen can modulate distribution and function of adrenergic receptors in the heart of different species. We reported here gender differences in adrenergic responsiveness of electrically driven guinea pig left atria.

Methods: Experiments were performed on the guinea pigs divided in four groups: males control (MC), males treated by 17-beta-estradiol (MTE), females control (FC) and females treated by tamoxifen (FTT).

Selective inhibition of pinacidil effects by estrogen in guinea pig heart.

Background: Recently, gender related differences in heart function have been extensively studied. Some of them, as differences in repolarization between males and females have been explained by direct effect of estrogen on delayed rectifier K+ channels and Ca2+ channels. It seems that estrogen induces overexpression of SUR2A subunits of ATP-sensitive K+ channels.

Gender differences in effects of pinacidil but not diazoxide on heart automatism in the isolated guinea pig right atria.

Unlabelled: The aim of this paper was to investigate the effects of pinacidil and diazoxide, the activators of sarcolemmal and mitochondrial ATP-sensitive K(+) channels (K(ATP)), respectively, on heart rate and force of contraction in female and male guinea pigs. Experiments were performed on the isolated, spontaneously beating, right atria obtained from guinea pigs of both genders. First series of experiments were performed in the spring and repeated in the fall.