Na-K ATPase activity in murine glucocorticoid induced polycystic kidney disease in vivo.

The prevalence and severity of polycystic kidney disease (PKD) induced by glucocorticoids in mice can be predicted by a mathematical "threshold" model. We studied the relationship between Na-K ATPase activity and cyst formation in C3H (low threshold for PKD) and DBA mice (high threshold). There was no difference in Na-K ATPase induction by 200 mg/kg methyl prednisolone acetate (MPA) (C3H; 97.4 nmol NADH/min/mg protein: DBA; 94.2 nmol NADH/min/mg protein). C3H mice demonstrated greater cyst formation than DBA animals as measured by area (20.1% relative area vs 13.9%, p < 0.05) or by calculated volume (7.4% relative volume vs 2.3%, p < 0.001). Significant relationships were seen between Na-K ATPase activity and logarithmically transformed area data in C3H animals and with cyst volume in both strains. Na-K ATPase activity is related to cyst formation in glucocorticoid induced PKD, but the level of Na-K ATPase activity is not a determinant of the threshold for glucocorticoid induced PKD.