Fig. 5. Frequency-dependent effects of steroids on contractile force by ventricle strips from both male (A) and female (B) rainbow trout. Effects of 11-ketotestosterone (11KT), testosterone (T), cortisol (C) and estradiol (E2) are shown over physiological frequencies (0.2–1.0 Hz). Only strips contracting at 0.5 and 0.8 Hz responded significantly to steroids. All values are means + S.E.M. (N=6–8). *P<0.05, all steroid-treated strips versus EtOH control strips; **P<0.01, all steroid-treated strips versus EtOH control strips; P<0.05, steroid-treated strips at 0.5 Hz versus steroid-treated strips at 0.2, 0.8 and 1.0 Hz.