UNILATERAL NEPHRECTOMY SELECTIVELY STIMULATES PHOSPHOLIPASE-D IN THE REMAINING KIDNEY

The activation of phospholipase D in the kidney could be detected in v ivo in rats treated with ethanol by the accumulation of phosphatidylet hanol. Unilateral nephrectomy stimulated the activity of phospholipase D in the remaining kidney as indicated by an increase in the level of phosphatidylethanol. A significant increase in phosphatidylethanol le vel was observed as early as 5 min after contralateral nephrectomy and peak accumulation (200% of control) was observed after 15 min. The ph osphatidylethanol level decreased again to the basal level after 2 h. The accumulation of phosphatidylethanol was specific for kidney and th e product was localized primarily in the cortex. Phospholipase D activ ity in kidney cortical slices from untreated rats was stimulated in vi tro by plasma obtained from unilaterally nephrectomized rats, indicati ng that circulating factors in the plasma are responsible for the acti vation of phospholipase D. The phospholipase D activation by plasma fr om uninephrectomized animals was selectively inhibited by the tyrosine kinase inhibitor genistein, but not by the protein kinase C inhibitor H7. It is concluded that phospholipase D activity is stimulated as an early signal transduction event in compensatory kidney growth.