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 (Δ F / 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 m m KCl at two different Ca 2+ concentrations. 17β‐Oestradiol at the highest concentration tested (30 μ m ) 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 μ m ) 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.