INOSITOL 1,4,5-TRISPHOSPHATE RECEPTOR FUNCTION IN NEONATAL CARDIOMYOCYTES

We have previously reported that the metabolism of inositol(1,4,5)tris phosphate (Ins(1,4,5)P-3)is altered when rat neonatal ventricular cardiomyocytes are isolated and cultured. In the current study we show that the mass content of Ins(1,4,5)P-3 is lower in the isolated cells than in the intact tissue. However, the properties of the Ins(1,4,5)P-3 receptors were not different in the two preparations and the isolated cells remained insensitive to Ins(1,4,5)P-3 in terms of Ca-45(2+) release. Thus, despite the altered pattern of metabolism of Ins(1,4,5)P-3 in isolated neonatal cells, the properties of the receptors were similar to those reported in other myocardial preparations.