[Influence of corticosteroid on phosphatidylinositol turnover in aminonucleoside-induced nephrotic rat kidney].

To clarify the changes in the intracellular signal transduction system in the kidneys of aminonucleoside (AN)-induced nephrotic rats and the effect of steroid on these changes, we investigated the urinary protein excretion and PGE2 excretion with and without steroid administration as well as the metabolic turnover system of phosphatidylinositol (PI), which is one of the intracellular signal transduction systems mediated by the PGE2 receptor of the glomerulus isolated from the kidney. The following results were obtained: (10 The action of steroid in inhibiting proteinuria was not correlated with its action in inhibiting PGE2 production. (2) Enhanced PI turnover of the glomerulus isolated from the kidney was observed in the state of nephrosis. (3) Sensitivity of the PI turnover system to PGE2 was changed both in the state of nephrosis and after the disappearance of proteinuria, indicating the possible action of steroid in modifying the change. From the above, it was suggested that change in the PI turnover system of the glomerulus isolated from the kidney is deeply involved in the onset and recurrence of nephrosis.