Thyroid hormones stimulate Na+-Pi transport activity in rat renal brush-border membranes: role of membrane lipid composition and fluidity.
Antecedent studies have suggested that lipid composition and fluidity of cellular membranes of various organs are altered in response to thyroid hormone status. To date, the effects of thyroid hormone status on these parameters have not been examined in rat renal apical membrane in regard to sodium-dependent phosphate transport. In the present study, we determined the potential role of alterations in cortical brush-border membrane lipid composition and fluidity in modulation of Na+-Pi transport activity in response to thyroid hormone status. Thyroid hormone status influences the fractional excretion of Pi, which is associated with alteration in renal brush-border membrane phosphate transport. The increment in Na+-Pi transport in renal BBMV isolated from Hyper-T rats is manifested as an increase in the maximal velocity (Vmax) of Na+-Pi transport. Further, the cholesterol content was significantly increased in renal BBM of Hypo-T rats and decreased in Hyper-T rats as compared to the Eu-T rats. The molar ratio of cholesterol/phospholipids was also higher in renal BBM from hypo-T rats. Subsequently, fluorescence anisotropy of diphenyl hexatriene (rDPH) and microviscosity were significantly decreased in the renal BBM of the Hyper-T rats and increased in the Hypo-T rats as compared to Eu-T rats. The result of this study, therefore, suggest that alteration in renal BBM cholesterol, cholesterol/phospholipid molar ratio, and membrane fluidity play an important role in the modulation of renal BBM Na+-Pi transport in response to thyroid hormone status of animals.
Prasad
Rajendra
R
Department of Biochemistry, Postgraduate Institute of Medical Education and Research, Chandigarh, India. fateh1977@yahoo.com
Kumar
Vivek
V
D000818:Animals; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism*; D007672:Kidney Cortex / Q000378:metabolism*; D008297:Male; D008560:Membrane Fluidity / Q000502:physiology*; D008563:Membrane Lipids / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000378:metabolism*; D013963:Thyroid Hormones / Q000502:physiology*
D008563:Membrane Lipids; D010710:Phosphates; D013963:Thyroid Hormones; D012964:Sodium
Biochim Biophys Acta. 1996 Oct 2;1284(1):69-78
8865817
Am J Physiol. 1999 Apr;276(4 Pt 1):E774-82
10198316
Am J Physiol. 1987 Jun;252(6 Pt 1):G762-7
3035939
Biochim Biophys Acta. 1981 Nov 6;648(2):247-53
7306539
J Lipid Res. 1985 Sep;26(9):1015-35
3906008
J Lab Clin Med. 1953 Mar;41(3):486-92
13035283
Am J Physiol. 1988 Dec;255(6 Pt 2):F1183-90
3202182
Biochem J. 1988 Mar 15;250(3):865-9
2839148
Biochim Biophys Acta. 1978 Dec 15;515(4):367-94
365237
Biochim Biophys Acta. 1988 Apr 7;939(2):189-96
3128322
Surgery. 1996 Aug;120(2):138-43
8751575
J Biol Chem. 1988 Aug 15;263(23):11183-8
3403520
Am J Physiol. 1985 Jul;249(1 Pt 2):F12-9
3160247
Prog Lipid Res. 1988;27(3):199-270
3075762
Am J Physiol. 1989 May;256(5 Pt 2):F852-61
2524168
Anal Biochem. 1977 Dec;83(2):346-56
603028
Proc Natl Acad Sci U S A. 1985 Jun;82(11):3606-10
2987936
J Biol Chem. 1980 May 25;255(10):4474-80
7372588
Am J Physiol. 1993 Aug;265(2 Pt 2):F323-6
8368342
J Lipid Res. 1981 Feb;22(2):323-38
7240961
Am J Physiol. 1984 Feb;246(2 Pt 2):F133-9
6696115
Am J Physiol. 1989 Jan;256(1 Pt 2):F85-94
2912170
Science. 1989 Apr 7;244(4900):76-9
2539642
Prog Biophys Mol Biol. 1984;43(3):195-257
6087406
Endocrinology. 1985 Jun;116(6):2438-49
2986951
J Endocrinol. 1998 Oct;159(1):9-14
9795336
Nature. 1986 Dec 18-31;324(6098):641-6
2879243
Biochim Biophys Acta. 2002 Apr 24;1586(3):331-43
11997084
Science. 1988 Jan 15;239(4837):268-75
3276003
Biochemistry. 1987 Mar 24;26(6):1746-56
3593687
Biochim Biophys Acta. 1991 Nov 13;1071(3):255-71
1958689
J Biol Chem. 1960 Mar;235:769-75
13793161
Biochemistry. 1979 Sep 18;18(19):4136-44
39592
Am J Kidney Dis. 1996 Feb;27(2):195-8
8659492