Plasma Phospholipase A 2 Activity in Nephrectomized Rats and the Question of Renin Inhibition

Summary

Plasma from 48-hr nephrectomized or sham-nephrectomized rats was incubated with homologous ³²P-labeled PE (renin “preinhibitor”). After extraction of total lipids from the incubate and thin layer silica gel chromatography of the extract, radioactivity was recovered as PE or its deacylated derivative LPE (renin “inhibitor”). Nephrectomy did not cause a reduction in the proportion of counts recovered as LPE, suggesting that its rate of formation and degradation is normal. This suggests that plasma from nephrectomized rats should have no lack of renin “inhibitor” if it is formed from what are known to be undiminished circulating levels of “preinhibitor”. If the kidney is not the major source of circulating “preinhibitor” and does not affect availability of the “inhibitor”, its proposed renin-inhibitory role may be questioned. Alternatively, the phospholipid theory of renin inhibition is untenable in its present form.