31P-NMR of liver peroxisome membranes from normal and clofibrate-treated rats

Normal and clofibrate-induced rat liver peroxisomes were studied in order to correlate the drug-elicited modifications of membrane permeability and fluidity with changes of the phospholipid component. The phospholipid composition and membrane fluidity of purified peroxisomal fractions from control and test animals were evaluated by 31P-NMR and fluorescence polarization spectroscopic techniques. The ultrastructural, enzymatic and electrophoretic analyses confirmed that the drug was able to induce: i) peroxisome proliferation; ii) increase of the catalase and fatty acyl CoA beta-oxidation system (FAOS) activities, and iii) neosynthesis of the 69 kDa peroxisomal membrane protein (PMP). The distribution pattern of the peroxisomal enzymes and the fluorescence polarization values of anilinonaphthalene-8-sulfonate (ANS)-labelled peroxisomes, suggests that the membrane permeability and fluidity are altered, while 31P-NMR spectroscopy seems to indicate that the phospholipid composition and the phospholipid/lysophospholipid ratio do not vary between test and control samples.