PATHOPHYSIOLOGY OF VASCULAR SMOOTH-MUSCLE IN RENIN PROMOTER-T-ANTIGEN TRANSGENIC MICE

The pathophysiological consequence of targeted production of SV-40 T-antigen to renin-expressing cells in the kidney of transgenic mice is reported. A histopathologic analysis of the kidney from adult transgenic mice (12-16 wk old) revealed the presence of severe vascular lesions manifested by marked atypical hyperplasia of vascular smooth muscle. The levels of plasma renin, kidney renin, and kidney renin mRNA were examined in 6- and 9-wk-old transgenic mice and were found to be significantly lower than their age-matched nontransgenic littermates and were nonresponsive to captopril treatment. However, there was no significant difference in conscious mean arterial pressure between transgenic and nontransgenic mice. The levels of renal renin mRNA in transgenics and nontransgenic littermates were compared throughout ontogeny and were found to be equal in newborns, elevated 3- to 5-fold in 1-wk-old transgenics, and yet decreased 10-fold by 6 wk of age in transgenic mice. Expression of the transgene in the kidney exhibited the proper developmental pattern and was properly restricted to juxtaglomerular cells in neonatal mice. Nevertheless, in adult mice, T-antigen-containing cells were found throughout the entire renal arterial tree. The observed ability of renal vascular cells to be recruited to express both renin and T-antigen suggests a mechanism that can explain the development of the renal pathology in these mice.