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. (C) 2000 Federation of European Biochemical Societies.

This work was supported by grants from DGES Nos. PB97-0047 and PB98-0090 to C.M.; and DGICYT PB94-0150 and Plan Nacional de Investigación I+D No. 2FD97-0388-C02-01 and Fundación Teófilo Hernando, to A.G.G.

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