EFFECT OF PRAERUPTORIN-C ON SPONTANEOUS [CA2-CELLS OF NEONATAL RATS(](I) TRANSIENTS IN CULTURED MYOCARDIAL)

AIMS: To study the effects of praeruptorin C (Pra-C) on [Ca2+](i) tran sients in cultured neonatal myocardiocytes. METHOD: Using Ca2+-sensiti ve fluorescent indicator, Fura 2-AM, spontaneous cytosolic Ca2+ transi ents were measured in cultured myocardial cells of neonatal rats. RESU LTS: Pra-C 10, 30 mu mol . L(-1) caused a decrease in the peak of Ca2 transients. Pra-C 30 mu mol . L(-1) and 10 - 30 mu mol . L(-1) inhibi ted partly the stimulatory effects of CaCl2 4.8 mmol . L(-1) and Bay k 8644 100 nmol . L(-1) on peak Ca2+ transients, respectively. Pra-C di d not cause any marked change in the basal [Ca2+](i) level between bea ts. Pra-C inhibited the reduced [Ca2+](i) transients after inhibition of sarcoplasmic reticulum Ca2+ release in ryanodine pretreated cells. CONCLUSIONS: Pra-C inferred with the Ca2+ influx responsible for excit ation-contraction coupling in myocardiocytes.