1,25-Dihydroxyvitamin D stimulates sodium-dependent phosphate transport by renal outer cortical brush-border membrane vesicles by directly affecting membrane fluidity.
We examined the effects of several forms of vitamin D added to renal brush-border membrane suspensions on phosphate and glucose transport and on membrane fluidity. The 1,25-D stimulated and the other vitamin D decreased phosphate uptake. In contrast, glucose uptake was not affected by the treatment of vitamin D. The 1,25-D resulted in a significant shift of the lower transition temperature in Arrhenius plots for phosphate, but not for glucose uptakes, from 15 degrees C to 11.5 degrees C. These data indicate that the 1,25-D may alter membrane fluidity, limited to the phosphate transporter, thus affecting the phosphate uptake.
Suzuki
M
M
2nd Department of Internal Medicine, Jikei University School of Medicine, Tokyo, Japan.
Kawaguchi
Y
Y
Momose
M
M
Morita
T
T
Yokoyama
K
K
Miyahara
T
T
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002117:Calcitriol / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism; D007672:Kidney Cortex / Q000378:metabolism*; D008560:Membrane Fluidity / Q000187:drug effects*; D008871:Microvilli / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism*; D051381:Rats; D012964:Sodium / Q000494:pharmacology*; D013696:Temperature; D014807:Vitamin D / Q000378:metabolism / Q000494:pharmacology
D010710:Phosphates; D014807:Vitamin D; D012964:Sodium; D002117:Calcitriol; D005947:Glucose