title: Action potential stimulation reveals an increased role for P/Q-calcium channel-dependent exocytosis in mouse adrenal tissue slices.
abstract: Chromaffin cells of the adrenal medulla receive cholinergic input from the splanchnic nerve. Upon sympathetic activity, chromaffin cells fire action potentials that open voltage-gated calcium channels and evoke the exocytic release of catecholamines. Catecholamines then regulate homeostatic processes such as cardiac output and vascular tone. Thus control of the Ca(2+) influx in chromaffin cells represents a target for the regulation of multiple physiological functions. Previous reports utilized square pulse depolarizations to quantify the proportional exocytic response as a function of Ca(2+) channel subtype. In this study, we use perforated patch voltage clamp and action potential waveforms to depolarize cells in situ. We analyze Ca(2+) current components under conditions that match the dynamic native cell behavior. This approach revealed a greater role for P/Q-type calcium channels in evoked exocytosis than previously reported. Thus, the P/Q-type channels represent a more important control point for the regulation of catecholamine-dependent processes than previously believed.
authors.affiliation: Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106, USA.
authors.forename: Shyue-An
authors.initials: SA
authors.lastname: Chan
authors.forename: Luis
authors.initials: L
authors.lastname: Polo-Parada
authors.forename: Corey
authors.initials: C
authors.lastname: Smith
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000311:Adrenal Glands / Q000502:physiology* / Q000648:ultrastructure*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020865:Calcium Channels, P-Type / Q000502:physiology*; D020907:Calcium Channels, Q-Type / Q000502:physiology*; D002462:Cell Membrane / Q000502:physiology / Q000648:ultrastructure; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000502:physiology / Q000648:ultrastructure; D025802:Electric Capacitance; D004558:Electric Stimulation / Q000379:methods; D005089:Exocytosis / Q000502:physiology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL
chemical_list: D020865:Calcium Channels, P-Type; D020907:Calcium Channels, Q-Type; D002118:Calcium