Whole-cell Ca2+ channel currents were recorded employing the variant of the patch-clamp technique. The recording pipettes, fabricated from borosilicate glass (Garner Glass Co., Claremont, CA), were pulled on a P-97 micropipette puller (Sutter Instrument Co., Novato, CA). The Ca2+ currents were acquired with an Axopatch 200B amplifier (Molecular Devices, Sunnyvale, CA), equipped with an 18-bit analog-to-digital converter board (HEKA Instruments, Bellmore, NY). The currents were analog filtered at a frequency of 2 kHz (−3dB, 4-pole low-pass Bessel filter), and digitized with custom-designed S5 software developed by Stephen R. Ikeda, M.D., Ph.D. (Chief, Laboratory of Molecular Physiology, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD).
