title: Adrenal fasciculata cells express T-type and rapidly and slowly activating L-type Ca2+ channels that regulate cortisol secretion.
abstract: In whole cell patch-clamp recordings, we characterized the L-type Ca(2+) currents in bovine adrenal zona fasciculata (AZF) cells and explored their role, along with the role of T-type channels, in ACTH- and angiotensin II (ANG II)-stimulated cortisol secretion. Two distinct dihydropyridine-sensitive L-type currents were identified, both of which were activated at relatively hyperpolarized potentials. One activated with rapid kinetics and, in conjunction with Northern blotting and PCR, was determined to be Cav1.3. The other, expressed in approximately one-half of AZF cells, activated with extremely slow voltage-dependent kinetics and combined properties not previously reported for an L-type Ca(2+) channel. The T-type Ca(2+) channel antagonist 3,5-dichloro-N-[1-(2,2-dimethyl-tetrahydro-pyran-4-ylmethyl)-4-fluoro-piperidin-4-ylmethyl]-benzamide (TTA-P2) inhibited Cav3.2 current in these cells, as well as ACTH- and ANG II-stimulated cortisol secretion, at concentrations that did not affect L-type currents. In contrast, nifedipine specifically inhibited L-type currents and cortisol secretion, but less effectively than TTA-P2. Diphenylbutylpiperidine Ca(2+) antagonists, including pimozide, penfluridol, and fluspirilene, and the dihydropyridine niguldipine blocked Cav3.2 and L-type currents and inhibited ACTH-stimulated cortisol secretion with similar potency. This study shows that bovine AZF cells express three Ca(2+) channels, the voltage-dependent gating and kinetics of which could orchestrate complex mechanisms linking peptide hormone receptors to cortisol secretion through action potentials or sustained depolarization. The function of the novel, slowly activating L-type channel is of particular interest in this respect. Regardless, the well-correlated selective inhibition of T- and L-type currents and ACTH- and ANG II-stimulated cortisol secretion by TTA-P2 and nifedipine establish the critical importance of these channels in AZF cell physiology.
authors: Department of Neuroscience, Wexner Medical Center, The Ohio State University, Columbus, Ohio enyeart.1@osu.edu.
authors: John J
authors: JJ
authors: Enyeart
authors: Department of Neuroscience, Wexner Medical Center, The Ohio State University, Columbus, Ohio.
authors: Judith A
authors: JA
authors: Enyeart
mesh_terms: D000200:Action Potentials / Q000187:drug effects*; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000235:genetics* / Q000378:metabolism; D020747:Calcium Channels, T-Type / Q000235:genetics* / Q000378:metabolism; D002417:Cattle; D000242:Cyclic AMP / Q000494:pharmacology; D004095:Dihydropyridines / Q000494:pharmacology; D005484:Fluspirilene / Q000494:pharmacology; D015870:Gene Expression; D006854:Hydrocortisone / Q000378:metabolism*; D008839:Microelectrodes; D009543:Nifedipine / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D010395:Penfluridol / Q000494:pharmacology; D010868:Pimozide / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D059010:Single-Cell Analysis; D015383:Zona Fasciculata / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
chemical_list: C570743:3,5-dichloro-N-(1-(2,2-dimethyltetrahydropyran-4-ylmethyl)-4-fluoropiperidin-4-ylmethyl)benzamide; D001549:Benzamides; D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D020747:Calcium Channels, T-Type; D004095:Dihydropyridines; D010880:Piperidines; D020033:Protein Isoforms; D000804:Angiotensin II; D010868:Pimozide; D010395:Penfluridol; D000324:Adrenocorticotropic Hormone; D005484:Fluspirilene; D000242:Cyclic AMP; D009543:Nifedipine; D002118:Calcium; D006854:Hydrocortisone; C054074:niguldipine
keywords: ACTH; ANG II; Cav1.3; Cav3.2; L-type Ca2+ channel; TTA-P2; adrenal fasciculata; cortisol