Quercetin decreased heart rate and cardiomyocyte Ca2+ oscillation frequency in rats and prevented cardiac hypertrophy in mice.

Abstract

Aim: To study the effects of quercetin (Que) on myocardial excitation-contraction coupling and cardiac remodeling.

Methods: Left ventricles and femoral arteries of rats were cannulated for hemodynamic recording. Mouse cardiac hypertrophy was induced by abdominal aortic coarctation (AAC). Cultured myocardial cells in neonatal rats were loaded with Fura 2-AM. The intracellular calcium ([Ca2+]i) and spontaneous [Ca2+]i oscillations ([Ca2+]i-SO) were tested by AR-CM-MIC cation measurement system.

Results: Que 3 or 25 mg.kg-1 i.v. in rats decreased heart rate from (420 +/- 19) to (390 +/- 15) and (314 +/- 18) beat.min-1, respectively, companied with very modest changes in both left ventricular pressures (LVP) and its differential dpLV/dtmax. Que 10, 50, 250 mumol.L-1 concentration-dependently slowed the frequency of [Ca2+]i-SO in cultured myocardial cells from (26 +/- 4) to (25 +/- 3), (18 +/- 4), and (12 +/- 3) time.min-1, respectively, but did not change their resting [Ca2+]i or amplitudes of [Ca2+]i-SO. Similarly, the increases in frequency of [Ca2+]i-SO caused by either isoproterenol (Iso) or ouabain (Oua) were prevented by Que 100 mumol.L-1, while the simultaneous increases in amplitude of [Ca2+]i-SO remained. Besides, [Ca2+]i rises excited by angiotensin II (Ang II) but not high [K+]o were prevented by Que 100 mumol.L-1. Daily administration of Que 120 mg.kg-1 i.g. for 5 d markedly prevented the cardiac hypertrophy in AAC mice, without effects on the ventricular mass to body weight ratio (VM/BW) in sham-operated mice.

Conclusion: Que decreased myocardial [Ca2+]i-oscillation frequency and prevented cardiac remodeling, but had no direct effect on cardiac excitation-contraction coupling.