TY - JOUR
T1 - Mechanism of stimulation of renal phosphate transport by 1,25-dihydroxycholecalciferol
AU - Kurnik, Brenda R.C.
AU - Hruska, Keith A.
N1 - Funding Information:
The work on this manuscript was supported by grants from the NIH AM32087 and AM09976 and AM07126. The authors wish to thank Scott West-brook for his technical assistance and Karon Farris and Helen Odle for preparation of the manuscript. Dr. Keith Hruska is an Established Investigator of the American Heart Association.
PY - 1985/7/11
Y1 - 1985/7/11
N2 - Vitamin D has been shown to stimulate renal phosphate transport and to alter membrane phospholipid composition. The present studies examine the possibility that the effects of 1,25(OH)2D3 on phosphate transport are related to its effects on membrane lipids. Arrhenius plots, which relate maximum rates of sodium dependent phosphate uptake into brush-border membrane vesicles to temperature were constructed. Phosphate transport was studied using brush-border membrane vesicles from normal, vitamin D-deficient, and physiologically replete (15 pmol/100 g body weight per 24 h) rats. These plots were triphasic with characteristic, lipid-dependent, slopes (M1, M2, M3) representing activation energies and transition temperatures (T1, T2). Physiologic 1,25(OH)2D3 repletion normalized these plots by stimulating phosphate transport at all temperatures, increasing T2 from 18 ± 0.7 to 23.5 ± 0.9°C and decreasing M2 and M3 from -5.8 ± 0.2 and -10.2 ± 0.4 to -4.5 ± 0.4 and -7.7 ± 0.3, respectively. Pharmacologic (1.2 nmol/100 g per 3 h) 1,25(OH)2D3 treatment resulted in a change in the Arrhenius plot of phosphate transport to a biphasic one with a transition temperature of 30°C. This effect was not blocked by cycloheximide. The Arrhenius plots of glucose transport were triphasic and unchanged with vitamin D repletion. These data support a liponomic mechanism of action for 1,25(OH)2D3 on phosphate transport.
AB - Vitamin D has been shown to stimulate renal phosphate transport and to alter membrane phospholipid composition. The present studies examine the possibility that the effects of 1,25(OH)2D3 on phosphate transport are related to its effects on membrane lipids. Arrhenius plots, which relate maximum rates of sodium dependent phosphate uptake into brush-border membrane vesicles to temperature were constructed. Phosphate transport was studied using brush-border membrane vesicles from normal, vitamin D-deficient, and physiologically replete (15 pmol/100 g body weight per 24 h) rats. These plots were triphasic with characteristic, lipid-dependent, slopes (M1, M2, M3) representing activation energies and transition temperatures (T1, T2). Physiologic 1,25(OH)2D3 repletion normalized these plots by stimulating phosphate transport at all temperatures, increasing T2 from 18 ± 0.7 to 23.5 ± 0.9°C and decreasing M2 and M3 from -5.8 ± 0.2 and -10.2 ± 0.4 to -4.5 ± 0.4 and -7.7 ± 0.3, respectively. Pharmacologic (1.2 nmol/100 g per 3 h) 1,25(OH)2D3 treatment resulted in a change in the Arrhenius plot of phosphate transport to a biphasic one with a transition temperature of 30°C. This effect was not blocked by cycloheximide. The Arrhenius plots of glucose transport were triphasic and unchanged with vitamin D repletion. These data support a liponomic mechanism of action for 1,25(OH)2D3 on phosphate transport.
KW - (Rat kidney)
KW - Brush-border membrane
KW - Dihydroxycholecalciferol
KW - Kinetics
KW - Phosphate transport
KW - Vitamin D
UR - http://www.scopus.com/inward/record.url?scp=0022256114&partnerID=8YFLogxK
U2 - 10.1016/0005-2736(85)90066-5
DO - 10.1016/0005-2736(85)90066-5
M3 - Article
C2 - 3839137
AN - SCOPUS:0022256114
SN - 0005-2736
VL - 817
SP - 42
EP - 50
JO - BBA - Biomembranes
JF - BBA - Biomembranes
IS - 1
ER -