Inhibition of mitochondrial beta-oxidation and peroxisomal stimulation in rodent livers by valproate.

at 4°C. The precipitate was trapped on GF/A filters and putrescine incorporation was measured by liquid scintillation counting. Rat muscle TG was eluted from a DEAE-Sephacel column ( 13 mm X 1 10 mm) with a gradient of 0-0.5 M-NaCI in 40 ml of buffer A. Bovine liver cytosolic TG and human plasma factor XIIIA were eluted as standards. Stepwise extraction of TG resulted in the solubilization of most of the enzyme in high-salt/detergent medium (Table 1). The proportion solubilized in the first (cytosolic) extract was greater for nerve than for muscle. In synaptic but not extrasynaptic diaphragm. the major proportion of TG was solubilized only after inclusion of DTT in the medium. TG extracted at all steps exhibited absolute calcium-dependence. Cytosolic (C) and particulate (B) TG were eluted from DEAE-Sephacel at 0.35 and 0.15 M-NaCI, respectively. TGB was eluted later after DTT extraction. The results show that tissue-associated calcium-dependent TG activity in rat diaphragm is present mainly in the detergent-extractible particulate fraction, and is associated with both synaptic and extrasynaptic regions of the muscle. A prominent component of particulate TG in the synaptic region is tightly associated with insoluble protein and is extractable only with a thiol reagent. A similar fraction ( B I ) has also been demonstrated in rat lung 171. TG in phrenic nerve is partly of the cytosolic and partly of the particulate form. There is no DTT-labile component in nerve. I t may be concluded that a portion of particulate TG is associated with the neural region of diaphragm muscle. The findings are consistent with the hypothesis that particulate TG is localized within cytoskeleton or cell membranes at either prcor postsynaptic sites.