Effect of vasopressin on Na+ kinetics in cultured rat vascular smooth muscle cells.
The effect of arginine vasopressin (AVP) on Na+ kinetics was examined in cultured rat vascular smooth muscle cells (VSMC) and rat renal papillary collecting tubule cells (RPCT) by the direct measurement of intracellular sodium concentration [(Na+]i) using fluorescence dye; SBFI. AVP increased [Na+]i in a dose-dependent manner at a concentration of 10(-9) M or higher in rat VSMC but did not affect [Na+]i in rat RPCT. The calcium (Ca2+)-free solution completely blocked the increasing effect of AVP on [Na+]i in rat VSMC. A Ca2+ ionophore, ionomycin (1-2 x 10(-6) M) increased [Na+]i both in rat VSMC and RPCT. The Ca2(+)-free solution abolished the ionomycin-increased [Na+]i both in rat VSMC and RPCT. These results therefore indicate that after binding the V1 receptor AVP increases [Na+]i mediated through an increase in cellular Ca2+ uptake in VSMC.
Okada
K
K
Department of Medicine, Jichi Medical School, Tochigi, Japan.
Ishikawa
S
S
Saito
T
T
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000378:metabolism; D001127:Arginine Vasopressin / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology; D002478:Cells, Cultured; D004533:Egtazic Acid / Q000494:pharmacology; D007679:Kidney Medulla / Q000187:drug effects / Q000378:metabolism*; D007685:Kidney Tubules, Collecting / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism*
D001127:Arginine Vasopressin; D004533:Egtazic Acid; D012964:Sodium; D002118:Calcium