Inactivation of the Na, K-ATPase by radiation-induced free radicals. Evidence for a radical-chain mechanism.

Free radicals produced by water radiolysis were used to study the inactivation of the enzymatic activity of the Na,K-ATPase. A decrease of the activity to virtually zero with a mono-exponential dependence on the radiation dose was observed. The inactivation process is initiated by hydroxyl radicals.

Plasminogen activator inhibitor type 1 in rat spermatozoa: localisation in the tail, in the acrosome and on the surface of the head.

Isolated seminiferous tubules of rat testis contain considerable urokinase-inhibiting activity. An immunohistological analysis revealed the presence of plasminogen activator inhibitor type 1 (PAI-1) in the basement membrane as well as in the interior of the tubules. Distribution and intensity of the intratubular immunoreactivity depends on the stage of the seminiferous cycle.