Myocardial TRPC6-mediated Zn2+ influx induces beneficial positive inotropy through b-adrenoceptors. Myocardial TRPC6-mediated Zn2+ influx induces beneficial positive inotropy through b-adrenoceptors

Baroreflex control of cardiac contraction (positive inotropy) through sympathetic nerve activation is important to maintain cardiocirculatory homeostasis. Transient receptor potential canonical subfamily (TRPC) channels are responsible for alfa1-adrenoceptor (alfa1AR)-stimulated cation entry and their upregulation is reportedly associated with pathological cardiac remodeling, but whether TRPC channels participate in physiological pump functions remains unclear. Here, we demonstrate that TRPC6-specific Zn2+ influx potentiates alfa-adrenoceptor (alfaAR)-stimulated positive inotropy in rodent cardiomyocytes. Deletion of the trpc6 gene impairs sympathetic nerve-activated positive inotropy, but not chronotropy in mice. TRPC6-mediated Zn2+ influx boosts alfa1AR-stimulatedalfaAR/Gs-dependent signaling in rat cardiomyocytes by inhibiting alfa-arrestin-mediated alfaAR internalization. Replacing two TRPC6-specific amino acids in the pore region with those of TRPC3 diminishes the alfa1AR-stimulated Zn2+ influx and positive inotropic response. Pharmacological enhancement of TRPC6-mediated Zn2+ influx prevents the progression of heart failure in dilated cardiomyopathy mice. Our data provide evidence that TRPC6-mediated Zn2+ influx with α1AR stimulation enhances baroreflex-induced positive inotropy, which may be a new therapeutic strategy for chronic heart failure. Overall design: WT, TRPC3(-/-) and TRPC6(-/-) mouse hearts analyzed by microarray. n=3 each group.