The alpha1H subtype is the predominant T-type Ca2+ channel expressed in the adrenal zona glomerulosa of rats and bovines, exhibiting NiCl2 sensitivity with an IC50 of 6.4 +/- 0.2 microM.
The alpha1H subtype is the predominant T-type Ca2+ channel in the adrenal zona glomerulosa, mediating low voltage-activated currents.
The low voltage-activated (T-type) Ca2+ channel has been implicated in the regulation of aldosterone secretion from the adrenal zona glomerulosa by extracellular K+ levels, angiotensin II, and ACTH. However, the identity of the specific subtype mediating this regulation has not been determined. We utilized in situ hybridization to examine the distribution of three newly cloned members of the T-type Ca2+ channel family, alpha1G, alpha1H, and alpha1I, in the rat and bovine adrenal gland. Substantial expression of only the mRNA transcript for the alpha1H-subunit was detected in the zona glomerulosa of both rat and bovine. A much weaker expression signal was detected for the alpha1H transcript in the zona fasciculata of bovine. Whole cell recordings of isolated bovine adrenal zona glomerulosa cells showed the native low voltage-activated current to be inhibited by NiCl2 with an IC50 of 6.4 +/- 0.2 microM. Because the alpha1H subtype exhibits similar NiCl2 sensitivity, we propose that the alpha1H subtype is the predominant T-type Ca2+ channel present in the adrenal zona glomerulosa.
Schrier et al. (Thu,) conducted a other in Adrenal zona glomerulosa T-type Ca2+ channel expression. In situ hybridization and whole cell recordings was evaluated on Expression of alpha1G, alpha1H, and alpha1I mRNA transcripts and NiCl2 sensitivity. The alpha1H subtype is the predominant T-type Ca2+ channel expressed in the adrenal zona glomerulosa of rats and bovines, exhibiting NiCl2 sensitivity with an IC50 of 6.4 +/- 0.2 microM.