The beta subunits of voltage-dependent calcium channels are known to modify calcium channel currents through pore-forming alpha 1 subunits The beta 3 subunit is expressed in the adrenal gland and participates in forming various calcium channel types We performed a series of experiments in beta 3-null mice to determine the role of the beta 3 subunit in catecholamine release from the adrenal chromaffin system Protein levels of N-type channel forming CaV2 2 and L-type forming CaV1 2 decreased The beta 3-null mice showed a decreased baroreflex, suggesting decreased sympathetic tonus, whereas plasma catecholamine levels did not change. Pulse-voltage stimulation revealed significantly increased amperometrical currents in beta 3-null mice, while patch-clamp recordings showed a significant reduction in Ca2+-currents due to reduced L- and N-type currents, indicating facilitated exocytosis A biochemical analysis revealed increased InsP3 production In conclusion, our results indicate the importance of the beta 3 subunit in determining calcium channel characteristics and catecholamine release in adrenal chromaffin cells (C) 2010 Published by Elsevier Inc