PII: S1095-6433 Ž02.00177-0 Comparison of cardiac excitation–contraction coupling in isolated ventricular myocytes between rat and mouse

Transgenic animals offer many advantages for physiological study. The mouse is the most extensively utilized mammalian model for gene modification. Isolated ventricular myocytes are pivotal for assessment of cardiac function by allowing direct cellular and environmental manipulation without interference from compensatory mechanisms that may exist in vivo. This study was designed to compare the basic excitation–contraction coupling properties of mouse and rat ventricular myocytes. Cardiac myocytes were isolated from age- and gender-matched mice (FVB and C57BLy 6) and rats (Sprague–Dawley (SD) and Wistar). Mechanical and intracellular Ca properties were measured with an2q IonOptix SoftEdge system, including peak shortening (PS), time-to-PS (TPS), time-to-90 % relengthening (TR),90 maximal velocity of shortening and relengthening ("dLydt), and intracellular Ca fura-2 fluorescence intensity and2q decay rate (t). Resting cell length was variable among the different species or strains. PS from FVB group was significantly higher than the SD group. TPS and TR were significantly shorter in mice. qdLydt was similar among90 all groups whereas ydLydt was significantly faster in the C57BLy6 group compared to the rat groups. Resting intracellular Ca was lower in mice than in rats, and Ca-induced Ca release was variable among the four groups.2q 2q 2q Intracellular Ca decay was slower in Wistar compared to all other groups. The myocytes from C57BLy6 did not2q respond to increases in extracellular Ca. Myocytes from the FVB group exhibited a lesser reduction in PS in response2