CHARACTERIZATION OF A METHOD FOR THE DETECTION OF DRUGS WITH FREE-RADICAL SCAVENGING ACTIVITY USING PORCINE LEUKOCYTES

The effects of a range of free-radical scavenging drugs on luminol-enh anced chemiluminescence (CL) generated by porcine leukocytes, followin g activation by two nonreceptor-mediated stimulants, phorbol myristate acetate (PMA; a protein kinase activator) and ionomycin (a cation ion ophore), and by xanthine plus xanthine oxidase (X-XO), have been exami ned. Superoxide dismutase (0.1 units/mL) and catalase (50 units/mL) in hibited X-XO, but they were ineffective in leukocyte suspensions excep t at concentrations 500 times and 20 times higher. Sodium azide (10(-5 ) to 10(-3) M) caused a marked inhibition in CL production in activate d leukocytes, but not of X-XO CL. The antioxidants, glutathione (10(-3 ) M) and L-ascorbic acid (10(-3) M) were ineffective in activated leuk ocytes, but caused total inhibition of X-XO-induced CL. Mannitol (100 mM) had no effect on chemiluminescence in either system. Captopril (10 (-3) M) produced an inhibition of CL in both systems and this inhibiti on was significantly modified by pH. Thus, the present study has estab lished a standard screening procedure for the assessment of free-radic al scavenging activity using activated porcine leukocytes and xanthine -xanthine oxidase.