spun and the plasma levels of margatoxin were determined two ml of blood was separated over ficoll hypaque and the mnc were tested for pma ion induction as described above a representative experiment is shown in fig1 a yucatan mini pig received 25 u03bcg of margatoxin in 30 ml of vehicle 5 autologous serum in 1 1 saline to pbs solution over 2 5 h there was no significant rise in blood pressure or heart rate during infusion plasma level in this study peaked at 600 pm at the end of infusion and dropped to 100 pm at 4 5 h post infusion with half life of about 2 h margatoxin was undetectable in the plasma in 24 h plasma level of mgtx was determined in a competition binding assay by its inhibition of 125 i labeled mgtx binding to kv1 3 channels present in isolated plasma membranes unresponsiveness to pma ion was also maximal at the end of infusion and sustained for 4 5 h post infusion similar pharmokinetic study was performed six times with good correlations between high plasma levels of margatoxin and the lower response to pma ion yucatan mini pigs receiving vehicle had no significant fluctuation of responses to pma ion therefore this ex vivo test provides an assessment of the in vivo biological effect of margatoxin and can also be used to study the immunosuppressant effects of other ion channel blockers a representative graph of the inhibition by margatoxin of the delayed type hypersensitivity response to ppd tuberculin is shown in fig2 the yucatan mini pig was immunized with bcg 8 days 8 d prior.