Calcium waves in unstimulated left ventricular cardiomyocytes isolated from aged spontaneously hypertensive and normotensive rats

In this work, we described the incidence and the characteristics of calcium waves in cardiomyocytes isolated from aged normotensive rats (Wistar Kyoto, WKY) and age-matched spontaneously hypertensive rats (SHR) using imaging analysis of fura-2-loaded left ventricular cardiomyocytes. Left ventricular cardiomyocytes were isolated by enzymatic digestion from hearts of 18-20 month old WKY and aged-matched SHR. Intracellular calcium concentration did not differ in either strain, whereas the incidence of cells presenting calcium waves was greater in cardiomyocytes isolated from SHR. Moreover, cardiomyocytes isolated from SHR were significantly longer than those isolated from WKY. The calcium wave frequency was lower in SHR cardiomyocytes, while the velocity of the calcium waves was similar in both strains. Our results suggest that alterations in the calcium handling of SHR may contribute to the increased incidence of arrhythmias described in SHR hearts. (C) 1997 Academic Press.