Greater diversity than previously thought of chromaffin cell Ca2+ channels, derived from mRNA identification studies

Using reverse transcription followed by PCR amplification (RT-PCR), we have identified multiple messenger RNAs encoding for the neuronal pore-forming Ca2+ channel subunits alpha(1A) (P/Q channel), alpha(1B) (N channel), alpha(1D) (neuronal/endocrine L channel), alpha(1E) (R channel), alpha(1G-H) (T channel) and alpha(1S) (skeletal muscle L channel) in bovine chromaffin cells, mRNAs for the auxiliary beta(2), beta(3), beta(4), alpha(2)/delta and gamma(2) subunits mere also identified. In agreement with these molecular data, perforated patch-clamp recordings of whole-cell Ca2+ currents reveal the existence of functional R-type Ca2+ channels in these cells that were previously undetected with other techniques, Our results provide a molecular frame for a much wider functional diversity of Ca2+ channels in chromaffin cells than that previously established using pharmacological and electrophysiological approaches. (C) 2000 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.