Na+-H+ and Na+-Ca2+ exchange in glomerulosa cells: possible role in control of aldosterone production.
Sodium uptake by rat adrenal glomerulosa cells was stimulated by intracellular acidosis evoked by Na+-propionate. This process was inhibited by 5-(N,N-hexamethylene) amiloride (HMA), a known inhibitor of the Na+-H+ exchange. These experiments demonstrate the existence of the Na+-H+ exchange in glomerulosa cells. Although amiloride inhibited the angiotensin II- and adrenocorticotropic hormone (ACTH)-induced aldosterone response, HMA, a more specific inhibitor of Na+-H+ exchange, failed to do that. 45Ca2+ influx and efflux were dependent on intra- and extracellular Na+ concentrations. Amiloride analogues, known to inhibit Na+-Ca2+ exchange, reduced basal 45Ca influx. Although we could not reveal the activation of Na+-Ca2+ exchange by angiotensin II, inhibitors of Na+-Ca2+ exchange also inhibited the angiotensin- and ACTH-induced aldosterone response of glomerulosa cells. Our results suggest that Na+-Ca2+ exchange supports the maintenance of basal Ca2+ level in the cytoplasma of glomerulosa cells, and amiloride derivatives inhibit aldosterone production by reducing Ca2+ level below resting values.
Hunyady
L
L
Department of Physiology, Semmelweis University Medical School, Budapest, Hungary.
Kayser
S
S
Cragoe
E J
EJ
Balla
I
I
Balla
T
T
Spät
A
A
D000311:Adrenal Glands / Q000378:metabolism*; D000450:Aldosterone / Q000096:biosynthesis*; D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D002478:Cells, Cultured; D006859:Hydrogen / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism*; D019831:Sodium-Calcium Exchanger; D017923:Sodium-Hydrogen Exchangers
D002352:Carrier Proteins; D008565:Membrane Proteins; D019831:Sodium-Calcium Exchanger; D017923:Sodium-Hydrogen Exchangers; D000804:Angiotensin II; D000450:Aldosterone; D000584:Amiloride; D006859:Hydrogen; D012964:Sodium; D002118:Calcium