Ovariectomy enhances SR Ca2+ release and increases Ca2+ spark amplitudes in isolated ventricular myocytes

► We compare Ca2+ transients in ventricular myocytes from female mice with and without ovaries. ► Ovariectomy increases internal Ca2+ stores and Ca2+ release without affecting Ca2+ current. ► Ovariectomy increases Ca2+ spark size and frequency, without affecting spark width or duration. ► Sex steroid hormones may modulate unitary Ca2+ release in individual cardiac myocytes.