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

Abstract

Using reverse transcription followed by PCR amplification (RT‐PCR), we have identified multiple messenger RNAs encoding for the neuronal pore‐forming Ca²⁺ channel subunits α_1A (P/Q channel), α_1B (N channel), α_1D (neuronal/endocrine L channel), α_1E (R channel), α_1G‐H (T channel) and α_1S (skeletal muscle L channel) in bovine chromaffin cells. mRNAs for the auxiliary β₂, β₃, β₄, α₂/δ and γ₂ subunits were 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.