Biochemical effects of gentamicin on rat kidney cortex. I. Analytical subfractionation of control tissue

Detailed analytical subcellular fractionation of non-pregnant porcine corpus luteum reveals peroxisomes of normal size and significant UDP-glucuronosyltransferase activity in the high-speed supernatant

A detailed subfractionation of the non-pregnant porcine corpus luteum (CL) was performed employing differential centrifugation. Marker enzyme assays (i.e., lactate dehydrogenase for the cytosol, NADPH-cytochrome P450 reductase for the endoplasmatic reticulum, catalase (CAT) for peroxisomes, glutamate dehydrogenase for the mitochondrial matrix and acid phosphatase for lysosomes) in all subfractions obtained exhibited a pattern of distribution similar to that observed with rat liver. These subfractions should be useful in connection with many types of future studies. In disagreement with previous biochemical and morphological studies, peroxisomes (identified on the basis of catalase activity and by Western blotting of catalase and of the major peroxisomal membrane protein (PMP-70)) sedimented together with mitochondria (i.e., at 5000 x g(av) for 10 min) and not in the post-mitochondrial fraction prepared at 30,000 x g(av) for 20 min by Peterson and Stevensson. No other classical peroxisomal enzymes were detectable in the porcine ovary, raising questions concerning the function of peroxisomes in this organ. Furthermore, UDP-glucuronosyltransferase (UGT), generally considered to be an integral membrane protein anchored in the endoplasmatic reticulum, was recovered in both the cytosolic (i.e., the supernatant after centrifugation at 50,000 x g(av) for 1h) and the microsomal fraction of the porcine corpus luteum, even upon further centrifugation of the former. In contrast, UGT sediments exclusively in the microsomal fraction upon subfractionation of the liver and ovary from rat.

Effect of cyclosporin A and different vehicles on ATP production in mitochondria isolated from the rat kidney cortex

Isolated rat kidney mitochondria were exposed in vitro to cyclosporin A and three different vehicles, ethanol, DMSO and cremophor. Spontaneous ATP production and oxidative phosphorylation were measured with a bioluminometric method. Both ethanol and cremophor caused a slight (4-7%) decrease in spontaneous ATP production, and also cyclosporin A itself had a minimal effect. On the other hand DMSO had an opposite effect, causing an increase of about 20%. Cyclosporin A showed a dose dependent inhibition of oxidative phosphorylation, being most pronounced when dissolved in ethanol. Cremophor, the castor oil used in commercial preparations caused per se almost a 40% inhibition of the oxidative phosphorylation.