Isoflurane and cytochrome b5 stimulation of 2-chloro-1,1-difluoroethene metabolism by reconstituted rat CYP2B1 and CYP2C6.

Isoflurane stimulates the metabolism of 2-chloro-1,1-difluoroethene (CDE) in liver microsomes from phenobarbital-treated rats or rabbits. The P450 isozymes involved and the mechanism by which such stimulation occurs have not been clarified. The present study examined the effects of isoflurane and cytochrome b5 on CDE metabolism in reconstituted systems containing purified rat CYP2B1 or CYP2C6.

Effects of diabetes on calcium uptake by rat brush border membrane vesicles.

1. We investigated the mechanism of decreased transmucosal calcium transport in the gut of the diabetic rat by comparing calcium uptake by brush border membrane vesicles from control and streptozotocin diabetic rats at 5 days. Brush border calcium uptake consists of saturable and non-saturable components.

Isoflurane-chlorodifluoroethene interaction in human liver microsomes. Role of cytochrome P4502B6 in potentiation of haloethene metabolism.

Short-chain saturated halocarbons, including isoflurane and the chlorofluorocarbon substitute HCFC-123, can strongly potentiate the cytochrome P450-dependent oxidation of gaseous haloethenes, such as 2-chloro-1,1-difluoroethene (CDE) and vinyl chloride, in vivo and in vitro. P450 isozyme specificity in this effect is suggested by the fact that the interaction is pronounced in microsomes from rats treated with phenobarbital, but does not occur in microsomes of isoniazid- or beta-naphthoflavone-treated animals. We examined the effect of isoflurane on CDE defluorination in liver microsomes from 10 human organ donors to determine whether saturated halocarbon/haloethene interactions also occur in humans and, if so, to determine the cytochromes P450 involved.

Vitamin D and enterocyte brush border membrane calcium transport and fluidity in the rat.

Prior studies of vitamin D repletion showed a threefold increase in the maximum rate (Vmax) for calcium uptake by brush border membrane vesicles, but did not differentiate saturable and nonsaturable uptake components. We studied the calcium uptake and fluidity response of intestinal brush border vesicles to vitamin D by treatment with 1 alpha,25-dihydroxy-24,24-difluorocholecalciferol (24,24-F-1,25-(OH)2D3). Treatment responses were measured by effects on (1) saturable and nonsaturable initial uptake rates of calcium by rat proximal small intestinal brush border membrane vesicles; (2) transmucosal calcium transport by everted duodenal sac; and (3) fluorescence anisotropy.