Increased Na-K transport in glomerular mesangial cell membrane from spontaneously hypertensive rats.
To investigate the differences in the Na-K transport of the mesangial cell (MC) membrane in hypertension versus normotension, the activity of the Na-K pump and the passive cation permeability were measured in serially passaged cultured MC obtained from both spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. When Na-K pump was active, Na-K pump activity, described as ouabain-sensitive 86Rb uptake, was significantly greater in the cultured MC from SHR than WKY rats. The outward Na-K cotransport, described as the washout rate constant of bumetanide-sensitive 86Rb washout, was also greater in SHR MC than in WKY rat MC. When Na-K pump was inhibited by 1 mM ouabain, overall intracellular Na uptake was significantly greater in SHR MC. A greater 5-(N,N-hexamethylene)amiloride-sensitive Na uptake in SHR MC accounted for this difference. There was no difference in the intracellular concentration of Na and K in the cultured MC from the 2 strains when Na-K pump was active. It is concluded that there is an increased activity of Na-K pump in the cultured MC from SHR, and that this abnormality may be innate to SHR cells. It is also suggested that an increase in Na-K cotransport and Na-H antiport may explain this difference, and that these abnormalities observed in the SHR kidney may be involved in the pathogenesis of hypertension in this model.
Kuriyama
S
S
Second Department of Internal Medicine, Jikei University School of Medicine, Tokyo, Japan.
Nakamura
K
K
Kaguchi
Y
Y
Tomonari
H
H
Tokutome
G
G
Hashimoto
T
T
Sakai
O
O
D000818:Animals; D001693:Biological Transport, Active; D005920:Glomerular Mesangium / Q000378:metabolism*; D006973:Hypertension / Q000378:metabolism*; D008297:Male; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012413:Rubidium / Q000493:pharmacokinetics; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000502:physiology
D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium; D011188:Potassium