Atrial natriuretic peptide differentially modulates T- and L-type calcium channels

Atrial natriuretic peptide (ANP) inhibits the secretion of aldosterone stimulated by any of these major physiological agonists: angiotensin II, adrenocorticotropic hormone, or K+. The stimulatory actions of each of these agonists depend on calcium influx through voltage-dependent calcium channels. Because two types of calcium channels have been previously described in bovine glomerulosa cells (T- and L-type), the patch-clamp technique was used to evaluate the effect of ANP on each voltage-dependent calcium channel type. ANP was found to differentially modulate these two channel types, stimulating L-current while inhibiting T-current. Inhibition of T-current resulted from a shift in the voltage dependence of inactivation to more negative potentials within the physiological range. These results indicate that the ANP-induced inhibition of aldosterone secretion may be partially mediated via a reduction of the calcium current through T-type channels.