Cholesterol content and water and solute permeabilities of kidney membranes from aging rats.
The influence of the age-related increase in cholesterol content of kidney brush-border membranes on their water and solute permeabilities was studied in 10- and 24-mo-old male Wistar rats. These permeabilities were determined from the rate of shrinkage and swelling of brush-border vesicles using a stopped-flow apparatus coupled to a light transmission recording. Despite a 20% rise in total cholesterol per milligram proteins, the osmotic water permeabilities of the vesicles were unchanged between 10 (287 +/- 40 micron/s) and 24 mo (270 +/- 31 micron/s). In contrast, passive diffusions of NaCl and KCl, but not of urea, thiourea, and glycerol, were reduced by 35% between 10 and 24 mo. These results suggest that an increase in cholesterol content of kidney brush-border membrane decreases its salt permeabilities without altering the water pathways.
D000375:Aging / Q000378:metabolism*; D000818:Animals; D001834:Body Water / Q000378:metabolism*; D002463:Cell Membrane Permeability; D002784:Cholesterol / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism* / Q000502:physiology; D008297:Male; D008563:Membrane Lipids / Q000378:metabolism; D008871:Microvilli / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D008563:Membrane Lipids; D002784:Cholesterol