Renin promoter SV40 T-antigen transgenic mouse. A model of primary renal vascular hyperplasia.

Transgenic mice containing a ren-2 promoter T-antigen fusion construct (TAG+) develop renal vascular hypertrophy and hyperplasia associated with markedly suppressed renal renin mRNA, renal renin content, and plasma renin concentration. These animals are normotensive. In the present study, the renal and cardiovascular systems are characterized, revealing some surprising findings. Not only are the TAG+ mice normotensive in the face of pronounced renal pathology but also in the presence of an increase in plasma volume. These data raise interesting questions about blood pressure physiology and renal function of the TAG+ mice. Blood nitrogen urea of the TAG+ animal was markedly elevated and plasma creatinine level was in the normal range, indicating prerenal azotemia without renal failure. These findings are consistent with impaired renal perfusion with secondary volume expansion probably as the result of vascular hyperplasia. These transgenic animals provide a unique genetic model for studying the physiology of primarily renal vascular hyperplasia as well as blood pressure control in a low renin state.