Bumetanide-sensitive sodium-22 transport in vascular smooth muscle cell of the spontaneously hypertensive rat.
The effect of bumetanide, a known probe of Na+, K+ cotransport, on 22Na+ uptake and washout was examined in serially passed cultured vascular smooth muscle cells of spontaneously hypertensive rats (SHR), Wistar-Kyoto rats (WKY), and Wistar rats. In Ca2+-deficient medium, the drug exerted the greatest effect on 22Na+ washout in vascular smooth muscle cells from SHR and the least effect on cells from WKY. The respective mean values for the apparent bumetanide-sensitive 22Na+ washout rate constants (Ke; X 10(-2)/min) were 7.2, 4.3, and 1.7 for cells from SHR, WKY, and Wistar rats. In both 1 mM Ca2+ and Ca2+-deficient medium, in the presence of 1 mM ouabain, vascular smooth muscle cells from SHR had the highest plateau phase of 22Na+ uptake among the three cell preparations. All cells exhibited higher 22Na+ uptake in Ca2+-deficient medium than in 1 mM Ca2+ medium. Under this condition, bumetanide caused an additional rise in steady state 22Na+ uptake that was most pronounced in cells from SHR (21.3% versus 16.6% for Wistar rats and 4.8% for WKY). This finding indicates that a quantitatively greater inhibition of washout than of the uptake component of the bumetanide-sensitive 22Na+ transport occurs in Ca2+-deficient medium. It is concluded that, in Ca2+-deficient medium, the bumetanide-sensitive 22Na+ washout is higher in vascular smooth muscle cells of SHR than in those of normotensive controls and that this phenomenon reflects a higher Na+ turnover in vascular smooth muscle cell in the hypertensive rat strain.
A
A
Tokushige
M
M
Kino
H
H
Tamura
L
L
Hopp
B M
BM
Searle
A
A
Aviv
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002034:Bumetanide / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology; D004232:Diuretics / Q000494:pharmacology*; D004912:Erythrocytes / Q000378:metabolism; D006973:Hypertension / Q000378:metabolism*; D007700:Kinetics; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011919:Rats, Inbred Strains; D011921:Rats, Inbred WKY; D012964:Sodium / Q000378:metabolism*; D012979:Sodium Radioisotopes / Q000378:metabolism
D004232:Diuretics; D012979:Sodium Radioisotopes; D002034:Bumetanide; D010042:Ouabain; D012964:Sodium; D002118:Calcium