Expression of N-type calcium channels in human adrenocortical cells and their contribution to corticosteroid synthesis.
The inhibition of aldosterone activity is a useful approach for preventing the progression of cardiovascular and renal diseases in hypertensive patients. Although the results of our previous in vivo study suggested that N-type calcium channels may have a role in regulating plasma aldosterone levels, the direct relationship between N-type calcium channels and aldosterone production in adrenocortical cells has not been examined. In this study, the analysis of quantitative reverse transcription-PCR, western blotting, and immunocytological staining indicated the possible presence of N-type calcium channels in human adrenocortical cells (H295R cell line). Patch clamp analysis indicated that omega-conotoxin GVIA (CnTX), an N-type calcium channel inhibitor, suppressed voltage-dependent barium currents. During steroidogenesis, CnTX significantly reduced the transient calcium signaling induced by angiotensin II (Ang II) and partially prevented Ang II-induced aldosterone and cortisol formation with no significant influence on CYP11B2 and CYP11B1 mRNA expression. In addition, in α1B calcium channel subunits, knockdown significantly decreased Ang II-induced aldosterone formation with increments in CYP11B2 mRNA expression. We also investigated the inhibitory activities of some types of dihydropyridine calcium channel blockers (CCBs; cilnidipine: L-/N-type CCB, efonidipine: L-/T-type CCB, and nifedipine: L-type CCB), and these agents showed a dose-dependent inhibition effect on Ang II-induced aldosterone and cortisol production. Furthermore, only cilnidipine failed to suppress CYP11B1 expression in H295R cells. These results suggest that N-type calcium channels have a significant role in transducing the Ang II signal for aldosterone (and cortisol) biosynthesis, which may explain the mechanism by which N-type calcium channels regulate plasma aldosterone levels.
Aritomi
Shizuka
S
Research Center, Ajinomoto Pharmaceuticals, Kanagawa, Japan. shizuka_aritomi@ajinomoto.com
Wagatsuma
Hirotaka
H
Numata
Tomohiro
T
Uriu
Yoshitsugu
Y
Nogi
Yasuko
Y
Mitsui
Akira
A
Konda
Tomoyuki
T
Mori
Yasuo
Y
Yoshimura
Michihiro
M
D000302:Adrenal Cortex / Q000378:metabolism*; D000305:Adrenal Cortex Hormones / Q000096:biosynthesis*; D000804:Angiotensin II / Q000494:pharmacology; D001464:Barium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020864:Calcium Channels, N-Type / Q000096:biosynthesis*; D020013:Calcium Signaling / Q000187:drug effects; D002460:Cell Line; D019405:Cytochrome P-450 CYP11B2 / Q000378:metabolism; D004095:Dihydropyridines / Q000494:pharmacology; D006801:Humans; D013252:Steroid 11-beta-Hydroxylase / Q000378:metabolism; D020960:omega-Conotoxins / Q000494:pharmacology
D000305:Adrenal Cortex Hormones; D002121:Calcium Channel Blockers; D020864:Calcium Channels, N-Type; D004095:Dihydropyridines; D020960:omega-Conotoxins; D000804:Angiotensin II; D001464:Barium; D019405:Cytochrome P-450 CYP11B2; D013252:Steroid 11-beta-Hydroxylase