ANTI-MICROTUBULAR AGENTS AS INHIBITORS OF DESENSITIZATION TO CATECHOLAMINE STIMULATION OF ADENYLATE-CYCLASE IN EHRLICH ASCITES TUMOR-CELLS

Adenylate cyclase activity of the homogenate of Ehrlich ascites tumor cells pretreated with catecholamine at 37°C was not stimulated by the addition of the same catecholamine, whereas that of the cells without the pretreatment was stimulated. Such a desensitization was induced hardly at all when the pretreatment was performed at low temperature. The desensitization of adenylate cyclase activity to catecholamine stimulation was prevented by pretreatment. The effect of cholchine was dependent on the period of the treatment and concentration of colchicine. Vinblastine had a similar effect, whereas cytochalasin B was without effect. Thus, involvement of microtubules was suggested in the desensitization of the membrane-associated enzyme to external sitmulation. © 1979.