Further studies on the in vivo effect of cephaloridine on the stability of rat kidney lysosomes.

The stabilizing effect of cephaloridine, an antibiotic, on rat kidney lysosomal membranes was tested by a single subcutaneous injection. The release of two lyososomal enzymes, acid phosphatase and muramidase, was used as an index of lysosome membrane integrity. The levels of these enzymes in the kidney extracts as well as in the isolated kidney lysosome fractions were found to be raised considerably, compared to the controls. In rats treated with cephaloridine, the supernatant fraction obtained from the kidney homogenates, after centrifugation at 15,000 gav, contained lower enzyme activities than were found in the control animals. It is suggested that cephaloridine may inhibit the release of acid phosphatase and muramidase from rat kidney lysosomes and, therefore, may exert a stabilizing effect on the lysosomal membrane system. The possible mechanism of interaction of this antibiotic with rat kidney lysosomal membranes is proposed.