Unilateral Acute Renal Ischemia-Reperfusion Injury Induces Cardiac Dysfunction through Intracellular Calcium Mishandling

Background: Acute renal failure (ARF) following renal ischemia-reperfusion (I/R) injury is considered a relevant risk factor for cardiac damage, but the underlying mechanisms, particularly those triggered at cardiomyocyte level, are unknown. Methods: We examined intracellular Ca2+ dynamics in adult ventricular cardiomyocytes isolated from C57BL/6 mice 7 or 15 days following unilateral renal I/R. Results: After 7 days of I/R, the cell contraction was significantly lower in cardiomyocytes compared to sham-treated mice. It was accompanied by a significant decrease in both systolic Ca2+ transients and sarco/endoplasmic reticulum Ca2+-ATPase (SERCA(2a)) activity measured as Ca2+ transients decay. Moreover, the incidence of pro-arrhythmic events, measured as the number of Ca2+ sparks, waves or automatic Ca2+ transients, was greater in cardiomyocytes from mice 7 days after I/R than from sham-treated mice. Ca2+ mishandling related to systolic Ca2+ transients and contraction were recovered to sham values 15 days after I/R, but Ca2+ sparks frequency and arrhythmic events remained elevated. Conclusions: Renal I/R injury causes a cardiomyocyte Ca2+ cycle dysfunction at medium (contraction-relaxation dysfunction) and long term (Ca2+ leak), after 7 and 15 days of renal reperfusion, respectively.