Voltage-dependent Ca2+ channels provide a pathway for rapid influx of Ca2+ into cells, which plays a crucial role in both electrical and metabolic signaling.T-type currents are transduced via channel proteins encoded by three genes that compose a subfamily within the Cav channel family.The activity of T-type channels contributes to several known physiological and pathophysiological phenomena including burst firing in neurons, pace making activity in the heart and secretion from endocrine tissues. There are three cloned T-type channel isoforms. CaV3.1 (α1G) and CaV3.2 (α1H) are widely distributed whereas the expression of CaV3.3 (α1I) is restricted to the central nervous system.CaV3.1 and CaV3.2 are also expressed in the kidney, but little is known about their physiological role there. ATTO dyes are characterized by strong absorption (high extinction coefficient), high fluorescence quantum yield, and high photo-stability. The ATTO-594 fluorescent label belongs to the class of Rhodamine dyes and can be used with fluorescent equipment typically optimized to detect Texas Red and Alexa-594.