Figure 1. Ca²⁺-independent, microcystin-induced contraction of Triton-skinned rat caudal arterial smooth muscle.

Triton-skinned smooth muscle strips contracted in pCa 4.5 and relaxed in pCa 9 solution. Ca²⁺-induced contraction was repeated and relaxation effected again by a return to pCa 9 solution. Only the second Ca²⁺-induced contraction is shown here. Subsequent addition of microcystin (MC; 1 μM) at pCa 9 elicited a contractile response (n=9).