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

The aim of this study was to investigate the effect of 17β-oestradiol (E2) on detrusor smoothmuscle contractility and its possible neuroprotective role against ischaemic-like condition, whichcould arise during overactive bladder disease. The effect of E2 was investigated on rat detrusormuscle strips stimulated with carbachol, KCl and electrically, in the absence or presence ofa selective oestrogen receptor antagonist (ICI 182,780) and, by using confocal Ca2+ imagingtechnique, measuring the amplitude (F/F 0) and the frequency of spontaneous whole cellCa2+ 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 perfusedwith Krebs solution which underwent electrical field stimulation to stimulate intrinsic nerves;the amplitude and the frequency of Ca2+ flashes were also measured. 17β-Oestradiol exhibitedantispasmogenic activity assessed on detrusor strips depolarized with 60 mm KCl at two differentCa2+ concentrations. 17β-Oestradiol at the highest concentration tested (30 μm) significantlydecreased detrusor contractions induced by all the stimuli applied. In addition, the amplitudeand the frequency of spontaneous Ca2+ flashes were significantly decreased in the presence of E2(10 and 30 μm) compared with control detrusor strips. In strips subjected to A-G/R, a significantincrease in the amplitude of both spontaneous and evoked flashes was observed. 17β-Oestradiolwas found to increase the recovery of detrusor strips subjected to A-G/R. The ability of E2 tosuppress contraction in control conditions may explain its ability to aid recovery followingA-G/R.