Analysis of staphylococcal alpha toxin action in the taenia coli of the guinea pig

Abstract

The effects of staphylococcal alpha toxin were studied in taenia coli of the guinea pig by the sucrose gap method. The toxin evoked a dose-dependent depolarization, increase in action potential frequency and contraction during its contact time. Following removal of the toxin there was a block in responsiveness of the taenia toward 80 mM KCl or acetylcholine whereas the responsiveness toward histamine and BaCl 2 was only slightly reduced. Partial restoration of the excitability of the preparation was achieved by application of higher calcium concentrations. The effects of the toxin were similar to that of ouabain. On the depolarized preparation the toxin had no effect, the loosely bound fraction of membrane calcium being already released by depolarization. It is concluded that the toxin may release the loosely bound fraction of membrane calcium.