Figure 1. Cultured cardiac trabeculae continuously electrically stimulated to twitch contract at 1 Hz for 25 hours at a preload on only 1 mN/mm² in presence (ET-1, n = 17) and absence (Control, n = 14) of 1 nM ET-1.

Compared to control, in ET-1-treated muscles an enhanced active developed force was demonstrated (A), whereas time to peak force (B) and 90% of relaxation time (RT₉₀, C) were similar between two groups.