Differential regulation of Na(+),K(+)-ATPase and the Na(+)-coupled glucose transporter in hypertensive rat kidney.
Several Na(+) transporters are functionally abnormal in the hypertensive rat. Here, we examined the effects of a high-salt load on renal Na(+),K(+)-ATPase and the sodium-coupled glucose transporter (SGLT1) in Dahl salt-resistant (DR) and salt-sensitive (DS) rats. The protein levels of Na(+),K(+)-ATPase and SGLT1 in the DS rat were the same as those in the DR rat, and were not affected by the high-salt load. In the DS rat, a high-salt load decreased Na(+),K(+)-ATPase activity, and this decrease coincided with a decrease in the apparent Mechaelis constant (K(m)) for ATP, but not with a change of maximum velocity (V(max)). On the contrary, a high-salt load increased SGLT1 activity in the DS rat, which coincided with an increase in the V(max) for alpha-methyl glucopyranoside. The protein level of phosphorylated tyrosine residues in Na(+),K(+)-ATPase was decreased by the high-salt load in the DS rat. The amount of phosphorylated serine was not affected by the high-salt load in DR rats, and could not be detected in DS rats. On the other hand, the amount of phosphorylated serine residues in SGLT1 was increased by the high-salt load. However, the phosphorylated tyrosine was the same for all samples. Therefore, we concluded that the high-salt load changes the protein kinase levels in DS rats, and that the regulation of Na(+),K(+)-ATPase and SGLT1 activity occurs via protein phosphorylation.
Ikari
A
A
Department of Environmental Biochemistry and Toxicology, University of Shizuoka School of Pharmaceutical Science, 52-1 Yada, Shizuoka 422-8526, Japan. ikari@u-shizuoka-ken.ac.jp
Tachihara
Y
Y
Kawano
K
K
Suketa
Y
Y
D000818:Animals; D005947:Glucose / Q000378:metabolism; D006973:Hypertension / Q000378:metabolism*; D015151:Immunoblotting; D007668:Kidney / Q000378:metabolism*; D007700:Kinetics; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D020303:Rats, Inbred Dahl; D012964:Sodium / Q000378:metabolism; D051269:Sodium-Glucose Transporter 1; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics / Q000378:metabolism*
D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; C495676:Slc5a1 protein, rat; D051269:Sodium-Glucose Transporter 1; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D005947:Glucose