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 ca lcium waves in cardiomyocytes isolated from aged normotensive rats (Wi star Kyoto, WKY) and age-matched spontaneously hypertensive rats (SHR) using imaging analysis of fura-2-loaded left ventricular cardiomyocyt es. Left ventricular cardiomyocytes were isolated by enzymatic digesti on from hearts of 18-20 month old WKY and aged-matched SHR. Intracellu lar calcium concentration did not differ in either strain, whereas the incidence of cells presenting calcium waves was greater in cardiomyoc ytes isolated from SHR. Moreover, cardiomyocytes isolated from SHR wer e significantly longer than those isolated from WKY. The calcium wave frequency was lower in SHR cardiomyocytes, while the velocity of the c alcium waves was similar in both strains. Our results suggest that alt erations in the calcium handling of SHR may contribute to the increase d incidence of arrhythmias described in SHR hearts. (C) 1997 Academic Press.