Effect of venous stasis and physical exercise on plasma extracellular-superoxide dismutase.

The secretory protein extracellular-superoxide dismutase is the major superoxide dismutase (SOD) isoenzyme in the extracellular space. There is evidence to suggest that most extracellular-superoxide dismutase in the vascular system is bound to endothelial cell surfaces. Venous stasis and physical exercise is known to induce release of several endothelium-associated factors into the plasma. However, venous stasis and physical exercise were not found to induce any release of extracellular-superoxide dismutase into plasma. The plasma activity of the intracellular isoenzyme CuZn SOD was doubled by venous stasis.