The effects of maitotoxin on phosphoinositides and calcium metabolism in a primary culture of aortic smooth muscle cells

Abstract

P. Berta, S. Phaneuf, J. Derancourt, J. Casanova, M. Durand-Clement, C. le Peuch, J. Haiech and J.-C. Cavadore. The effects of maitotoxin on phosphoinositides and calcium metabolism in a primary culture of aortic smooth muscle cells. Toxicon 26, 133 – 141, 1988. — Maitotoxin, a potent marine toxin isolated from toxic tropical dinoflagellates and poisonous fishes induces contraction of different smooth muscle preparations. Actions of maitotoxin on phosphoinositides and calcium metabolism were studied using a primary culture of aortic smooth muscle cells. Maitotoxin induced a very large increase of cytosolic calcium concentration as evaluated by fura-2 acetoxymethyl ester fluorescence. This increase was concomitant with stimulation of inositol-phosphate accumulation and loss of viability of aortic smooth muscle cells. These responses to maitotoxin were abolished in Ca 2+-free medium, and were mimicked by saponin. Calcium ionophores or K + depolarisation did not induce inositol-phosphate formation. These results suggest that maitotoxin acts by altering smooth muscle cells permeability allowing a sustained calcium influx which is able to activate inositol-phosphate formation and which is lethal for the cells.