Effects of L-arginine in rat adrenal cells: involvement of nitric oxide synthase

CYMERYNG, CORA BEATRIZ; DADA LA; COLONNA, C; MENDEZ, C; PODESTÁ, EJ

ENDOCRINOLOGY

ENDOCRINE SOC

Año: 1999 vol. 140 p. 2962 - 2967

0013-7227

The effects of L-arginine on corticosterone production, cGMP, and nitrite levels were examined in zona fasciculata adrenal cells. L-Arginine significantly decreased both basal and ACTH-stimulated corticosterone production. This effect was still evident when steroidogenesis was induced by 8-bromo-cAMP and 22(R)-hydroxycholesterol, but not in the presence of exogenously added pregnenolone. L-Arginine increased cGMP and nitrite levels; these effects were blocked by the nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl-ester. Transport of L-[3H]arginine was rapid, saturable, and monophasic, with an apparent Km of 163 6 14 mM and a maximum velocity of 53 6 6 pmol/minz105 cells. The basic amino acids L-lysine and L-ornithine, but not D-arginine or the nitric oxide synthase inhibitors NG-nitro-L-arginine methyl-ester and NG-nitro-L-arginine, impaired L-arginine uptake. Taken together, these results suggest that steroidogenesis in zona fasciculata adrenal cells may be negatively modulated by L-arginine-derived nitric oxide. (Endocrinology 140: 2962?2967, 1999)