Reference

1,25-Dihydroxycholecalciferol stimulates renal phosphate transport by directly altering membrane phosphatidylcholine composition

1,25-Dihydroxycholecalciferol stimulates renal phosphate transport by directly altering membrane phosphatidylcholine composition. Kurnik, Brenda R. C.; Huskey, Margaret; Hruska, Keith A. (Dep. Med., Washington Univ., St. Louis, MO 63110, USA). Biochim. Biophys. Acta, 917(1), 81-5 (English) 1987. CODEN: BBACAQ. ISSN: 0006-3002. DOCUMENT TYPE: Journal CA Section: 2 (Mammalian Hormones) Rat kidney brush border membrane vesicle phosphatidylcholine content was increased after incubation with liposomes composed of dioleoylphosphatidylcholine [4235-95-4] or b-linoleyl,g-palmitoylphosphatidylcholine [17708-90-6] and 1,25-dihydroxycholecalciferol [1,25(OH)2D3] [32222-06-3] (10-7 M). Vesicular phosphatidylcholine content was increased from control levels of 49.5 mg/mg protein to 56.9 and 58.5, resp., after treatment with the liposomes contg. 1,25(OH)2D3. When the vesicles were incubated with liposomes composed of b-linoleyl, g-palmitoyl phosphatidylcholine, phosphate transport was stimulated from 231 to 431 pmol/mg protein/15 s in the presence of 1,25(OH)2D3 if the vesicles were derived from vitamin D-deficient rats and from 443 to 601 pmol/mg protein/15 s if the vesicles were prepd. from normal rats. Despite phosphatidylcholine transfer, incubation with liposomes composed of dioleoylphosphatidylcholine and 1,25(OH)2D3 did not stimulate phosphate transport. Furthermore, incubation of vesicles with liposomes and 1,25(OH)2D3 did not alter glucose transport.

Reconstitution of the microsomal ethanol-oxidizing system

Reconstitution of the microsomal ethanol-oxidizing system. Qualitative and quantitative changes of cytochrome P-450 after chronic ethanol consumption. Ohnishi, Kunihiko; Lieber, Charles S. (Lab. Liver Dis., Nutr. Alcohol., Bronx VA Hosp., New York, N. Y., USA). J. Biol. Chem., 252(20), 7124-31 (English) 1977. CODEN: JBCHA3. DOCUMENT TYPE: Journal CA Section: 4 (Toxicology) An EtOH [64-17-5]-oxidizing system was reconstituted with cytochrome P 450 [9035-51-2], NADPH-cytochrome c reductase [9023-03-4], and phospholipid. This system also metabolized PrOH [71-23-8], BuOH [71-36-3] and benzphetamine. Neither catalase nor alc. dehydrogenase plays a role in this sytem. Characteristics of this system are similar to those of the microsomal EtOH-oxidizing system. Chronic EtOH feeding of either male or female rats for 4 to 12 weeks resulted in significant quant. and qual. changes in hepatic cytochrome P 450. The absorption max. of CO-difference spectrum of cytochrome P 450 shifted to higher wavelength. Three hemoproteins were resolved by continuous buffer Na dodecyl sulfate-polyacrylamide gel electrophoresis of rat liver microsomes. Two of these increased after chronic EtOH feeding. One of these hemoproteins is distinct from those induced by phenobarbital or 3-methylcholanthrene treatment. On discontinuous buffer Na dodecyl sulfate-polyacrylamide gel electrophoresis there was a preferential increase of 2 proteins with apparent mol. wts. of 53,400 and 52,000, resp. These 2 proteins probably represent the apoproteins of the 2 hemoproteins increased after chronic EtOH feeding. The partially purified cytochrome P 450 from EtOH-fed rats was more active for alc. (EtOH, PrOH, BuOH) oxidn. than the control prepn. in the presence of excess NADPH-cytochrome c reductase and L-.alpha.-dioleoyl lecithin [4235-95-4]. There was no significant difference in the capacity of partially purified NADPH-cytochrome c reductase from either EtOH-fed rats or controls to promote alc. oxidn. in the presence of cytochrome P 450 and L-.alpha.-dioleoyl lecithin. Thus, the adaptive increase of the microsomal EtOH-oxidizing system activity after chronic EtOH consumption can be attributed, at least in part, to quant. and qual. changes of cytochrome P 450.