抄録
Heart rate is well known to be dependent on physical activity. However, its underlying signaling pathway of cardiac adaptation in response to voluntary exercise remains unclear. In this study, we investigated the role of the L-type Ca2+ channel in the heart of SPORTS rats, a novel hyper-running rat strain. Heart rate was significantly higher in SPORTS rats than those in control rats at sedentary condition by using the telemetric ECG recording technique. Cardiac hypertrophy was also observed in SPORTS rats. On the other hands, patch clamp studies revealed that L-type Ca2+ current was significantly larger in isolated neonatal SPORTS rat ventricular cardiomyocytes than in control myocytes. We confirmed the expression of L-type Ca2+ channel isoforms (Cav1.2, Cav1.3) mRNA in adult rat atrial and neonatal myocytes were significantly larger in SPORTS rat than those in control rat by 2.3-10 folds by quantitative real-time PCR. These results suggest that the L-type Ca2+ channel is a key modulator in congenital and exercise-adapted cardiac function in SPORTS rat featured by hyper-running activity. [J Physiol Sci. 2008;58 Suppl:S176]
