Fig. 7.

Effect of ISO, ET-1, and propranolol on the FFR in trabeculae. A: combination of ISO and ET-1 had no effect on FFR in intact trabeculae (n = 4). B: effect of ET-1 plus ISO on FFR in endocardial endothelium-denuded (EED) trabeculae. The muscles were treated with ET-1 (20 nmol/l) for 20 min before ISO (0.1 nmol/l) was added to the perfusion solution. Despite some recovery of force at all test stimulation frequencies, the slope of the FFR was not improved. C: propranolol (30 nmol/l) inhibited the FFR, especially at higher stimulation frequencies (n = 5).