title: Isolation of renal brush-border membrane vesicles by a low-speed centrifugation; effect of sex hormones on Na+-H+ exchange in rat and mouse kidney.
abstract: Na+-H+ exchange in rat and mouse renal brush-border membrane vesicles was studied by fluorescence quenching of the delta pH indicator, acridine orange. Brush-border membrane vesicles were isolated by a modified Mg/EGTA-precipitation method at low speed centrifugation (8000 X g). The enzymatic characteristics of these membrane vesicles were similar to those obtained by the original high-speed centrifugation method (Biber et al. (1981) Biochim. Biophys. Acta, 647, 169-176). The rates of Na+-H+ exchange in renal brush-border membrane vesicles from male and female rats were similar. Neither ovariectomy nor treatment of ovariectomized rats with estradiol or testosterone changed the activity of Na+-H+ exchanger. The rates of Na+-H+ exchange in the mouse were smaller than in the rat indicating the existence of species differences. Na+-H+ exchange in mouse renal brush-border membranes exhibit strong sex differences, the rates in the male being higher than in the female. Castration of male mice led to a decrease in Na+-H+ exchange to values found in females. Treatment of castrated mice with estradiol had no effect. In contrast, treatment with testosterone increased the rate of the exchanger by more than 100%. The effect of testosterone was restricted to the Vmax of the Na+-H+ exchanger, whereas the apparent Km for Na+ remained unchanged. Na+-dependent D-glucose transport in mouse renal luminal membranes exhibited also sex differences due to the potent stimulatory effect of testosterone. Therefore, Na+-H+ exchange and Na+-dependent D-glucose transport in the mouse kidney are under control of androgen hormones. This effect could be in close connection with the wellknown renotropic action of androgens in the mouse.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002469:Cell Separation; D002498:Centrifugation; D005260:Female; D012739:Gonadal Steroid Hormones / Q000494:pharmacology*; D006859:Hydrogen / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007668:Kidney / Q000378:metabolism* / Q000648:ultrastructure; D007700:Kinetics; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008871:Microvilli / Q000378:metabolism; D011073:Polyamines / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D012737:Sex Factors; D012964:Sodium / Q000378:metabolism*; D013045:Species Specificity
chemical_list: D012739:Gonadal Steroid Hormones; D011073:Polyamines; D006859:Hydrogen; D012964:Sodium; D002118:Calcium