Effects of 17β-oestradiol on rat detrusor smooth muscle contractility

The aim of this study was to investigate the effect of 17β-oestradiol (E(2)) on detrusor smooth muscle contractility and its possible neuroprotective role against ischaemic-like condition, which could arise during overactive bladder disease. The effect of E(2) was investigated on rat detrusor muscle strips stimulated with carbachol, KCl and electrically, in the absence or presence of a selective oestrogen receptor antagonist (ICI 182,780) and, by using confocal Ca(2+) imaging technique, measuring the amplitude (ΔF/F(0)) and the frequency of spontaneous whole cell Ca(2+) flashes. Moreover, the effect of 1 and 2 h of anoxia–glucopenia and reperfusion (A-G/R), in the absence or presence of the hormone, was evaluated in rat detrusor strips perfused with Krebs solution which underwent electrical field stimulation to stimulate intrinsic nerves; the amplitude and the frequency of Ca(2+) flashes were also measured. 17β-Oestradiol exhibited antispasmogenic activity assessed on detrusor strips depolarized with 60 mm KCl at two different Ca(2+) concentrations. 17β-Oestradiol at the highest concentration tested (30 μm) significantly decreased detrusor contractions induced by all the stimuli applied. In addition, the amplitude and the frequency of spontaneous Ca(2+) flashes were significantly decreased in the presence of E(2) (10 and 30 μm) compared with control detrusor strips. In strips subjected to A-G/R, a significant increase in the amplitude of both spontaneous and evoked flashes was observed. 17β-Oestradiol was found to increase the recovery of detrusor strips subjected to A-G/R. The ability of E(2) to suppress contraction in control conditions may explain its ability to aid recovery following A-G/R.