Renin inhibits the vasorelaxation induced by nitroso albumin

Nitrosated proteins exhibit actions characteristic of free NO. As the vasorelaxation effect of nitrosated albumin is rapidly inactivated in plasma, we postulated that a protease could remove or modify the NO attached to albumin. We found that the ability of plasma to inactivate the vasorelaxing action of NO-bovine serum albumin (NO-BSA) is restricted to a plasma fraction containing macromolecules. We also found that a crude preparation of renal renin also inactivated the vasorelaxation action of NO-BSA and UV-spectrophotometric analysis showed that the 335-nm signal of NO-BSA was significantly decreased by renin. This decrease could be prevented by a renin inhibitor or by immunodepleting the renin preparation with a monoclonal antibody to renin. The data suggest that renin accelerates the uncoupling of NO to albumin. Such a function may be important in the control of vascular tone and blood pressure.