[Cytoprotective effects of nicorandil on immature myocytes under hypothermic conditions]

We evaluated the functional and biochemical effects of nicorandil on cardiac myocytes incubated under hypothermic conditions. Cardiac myocytes were isolated from neonatal rat ventricles and cultured for 4 days. Myocytes (12.5 x 10(5) myocytes/flask) were then incubated at 4 degrees C for 24 hrs in media with nicorandil as follows: O M nicorandil (group C: control), 10(-5)M (group N 1), 5 x 10(-5)M (group N 2), 10(-4)M (group N 3). After hypothermic incubation, CPK and LDH were measured. The myocytes were then cultured for 24 hrs at 37 degrees C to evaluate the recovery of myocyte beating rate. For the beating rate, group N 3 showed a significantly increased recovery compared to the control (N 3: 44.2, p < 0.02, C: 24.6 percent of control; ie, beating rate prior to hypothermic incubation). The release of CPK and LDH was significantly suppressed in group N 3 compared to the control (N 3: 24.1, p < 0.005, 247.2, p < 0.01; C: 125.4 mIU/flask, 459.5 mIU/flask, respectively). Thus, nicorandil has cytoprotective effects on immature myocytes under hypothermic conditions.