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-enhanced chemiluminescence (CL) generated by porcine leukocytes, following activation by two nonreceptor-mediated stimulants, phorbol myristate acetate (PMA; a protein kinase activator) and ionomycin (a cation ionophore), and by xanthine plus xanthine oxidase (X-XO), have been examined. Superoxide dismutase (0.1 units/mL) and catalase (50 units/mL) inhibited X-XO, but they were ineffective in leukocyte suspensions except at concentrations 500 times and 20 times higher. Sodium azide (10(-5) to 10(-3) M) caused a marked inhibition in CL production in activated leukocytes, but not of X-XO CL. The antioxidants, glutathione (10(-3) M) and L-ascorbic acid (10(-3) M) were ineffective in activated leukocytes, 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 inhibition was significantly modified by pH. Thus, the present study has established a standard screening procedure for the assessment of free-radical scavenging activity using activated porcine leukocytes and xanthine-xanthine oxidase.