BOMBESIN STIMULATES TRANSPLASMA-MEMBRANE ELECTRON-TRANSPORT BY SWISS 3T3 CELLS

Bombesin, a mitogenic neuropeptide, stimulates transplasmalemma reduct ion of diferric transferrin or ferricyanide by Swiss 3T3 cells. The st imulation of diferric transferrin reduction occurs in the range of bom besin concentrations that stimulate proliferation of Swiss 3T3 cells. Diferric transferrin reduction by the 3T3 cells is accompanied by incr eased proton release from the cells and bombesin increases the diferri c transferrin-stimulated proton release twofold. Insulin increases the diferric transferrin reductase response and increases growth stimulat ion with bombesin. The effect of bombesin on the transmembrane electro n transport is a new aspect of its effect on the plasma membrane in ad dition to increase in phosphatidylinositol turnover and protein kinase c activation. The electron transport can provide an independent mecha nism of activation of the Na+/H+ exchange or it can change the redox s tate of pyridine nucleotide in the cytoplasm.