Résumé
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.