Potentiation by aldosterone of vasopressin-induced calcium kinetics in vascular smooth muscle cells.
1. The present study was undertaken to examine the effect of aldosterone on arginine vasopressin (AVP)-induced Ca2+ kinetics in cultured rat vascular smooth muscle cells (VSMC). The pre-incubation of cells with 1 x 10(-6) mol/L aldosterone for 24 h did not affect the basal cytosolic free Ca2+ [( Ca2+]i) but enhanced the AVP-induced mobilization of [Ca2+]i (1 x 10(-8) mol/L AVP; 287 vs 401, 1 x 10(-6) mol/L AVP; 430 vs 714 nmol/L). 2. The pre-incubation of cells with 1 x 10(-7) mol/L aldosterone for 24 h did not show this enhancing effect on the AVP-induced mobilization of [Ca2+]i. Without the preincubation, aldosterone did not change the basal [Ca2+]i or the AVP-induced mobilization of [Ca2+]i. This enhancement was still observed in the Ca2+-free solution containing 0.1 mmol/L EGTA (1 x 10(-8) mol/L AVP; 169 vs 341 nmol/L). 3. The enhancement by aldosterone of the AVP-mobilized [Ca2+]i was completely blocked by the simultaneous administration of 1 x 10(-4) mol/L spironolactone (1 x 10(-8) mol/L AVP; 258 vs 265 nmol/L). The treatment with aldosterone also stimulated the AVP-produced [45Ca2+] efflux during a 3 min period (1 x 10(-8) mol/L AVP; 32 vs 49, 1 x 10(-6) mol/L AVP; 50 vs 58% released from the resting intracellular [45Ca2+]-contents). 4. The present results indicate that aldosterone enhances the vascular action of AVP mediated through the stimulation of Ca2+ kinetics which may be dependent on the changes in the cellular signal transduction systems.
Okada
K
K
Department of Medicine, Jichi Medical School, Tochigi, Japan.
Ishikawa
S
S
Saito
T
T
D000450:Aldosterone / Q000494:pharmacology*; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D001127:Arginine Vasopressin / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism; D004357:Drug Synergism; D016257:Fura-2 / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D000451:Mineralocorticoid Receptor Antagonists / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013148:Spironolactone / Q000494:pharmacology
D000451:Mineralocorticoid Receptor Antagonists; D001127:Arginine Vasopressin; D013148:Spironolactone; D000450:Aldosterone; D002118:Calcium; D016257:Fura-2