Angiotensin actions on the isolated rat uterus during the estrous cycle:: Influence of resting membrane potential and uterine morphology

The involvement of AT(1) and AT(2) receptor subtypes in the response of the isolated rat uterus to angiotensin 11 (AngII) was studied throughout the estrous cycle. The AngII potency varied during the different estrous cycle phases, as indicated by significantly different pD(2) values. No significant differences were observed in AngII metabolism among different estrous phases. Morphological analysis indicated that external and internal myometrium layers were thicker during estrus. In addition, the highest resting membrane potential was also observed during this phase, when compared with the proestrus and diestrus phases. The AngII-induced uterine contractions were blocked by losartan. Different losartan pD(2) values were observed. PD123319 had no effect on the contractile response to AngII. The results also indicate that estrous cycle-dependent changes in AngII potency are correlated with uterine morphological and/or membrane potential changes. Copyright (C) 2002 S. Karger AG, Basel.