[Effects of delsoline on beating rate of cultured rat myocardial cells].
Cells from neonatal rat ventricular myocardium were cultured in Eagle MEM. After the cells were exposed to delsoline (DS) 0.5 and 0.75 mmol/L for 15 min, the beating rate increased by 7+/-7 and 10+/-9%, respectively. At 2.5 mmol/L, the beating rate decreased by 43+/-30%, while the amplitude of contraction was diminished. The increase in spontaneous frequency induced by DS 0.75 mmol/L was antagonized by propranolol 0.01 mmol/L. But propranolol per se did not alter the beating rate. The positive chronotropic responses of isoproterenol 1 micromol/L were reversed by DS 1 mmol/L.