dibutyryl-cyclic-gmp and Carcinoma--Ehrlich-Tumor

Ehrlich cell plasma membrane ferricyanide reductase activity increased in the presence of mastoparan, a generic activator of G proteins, using either whole cells or isolated plasma membrane-fractions. Agents that increase intracellular cAMP also increased the rate of ferricyanide reduction by Ehrlich cells. For the first time, evidence is shown on a modulation of plasma membrane redox system by cGMP. In fact, permeant analogs of cGMP, dibutyryl cGMP, and 8-bromo-cGMP increased the rate of ferricyanide reduction by the Ehrlich cell plasma membrane redox system. Furthermore, specific inhibition of cGMP-phosphodiesterases by dipyridamole was also accompanied by an enhancement in the rate of ferricyanide reduction. On the other hand, treatments expected to increase cytoplasmic Ca2+ concentrations were accompanied by a remarkable stimulation of the reductase activity. Taking all these data together, it seems that the Ehrlich cell plasma membrane redox system is under a multiple and complex regulation by different signal transduction pathways involving G proteins, cyclic nucleotides, and Ca2+ ions.

Topics: Animals; Bucladesine; Calcimycin; Calcium; Calcium-Transporting ATPases; Carcinoma, Ehrlich Tumor; Cell Membrane; Cyclic GMP; Dibutyryl Cyclic GMP; Enzyme Inhibitors; Female; Kinetics; Mice; NADH, NADPH Oxidoreductases; Neomycin; Oxidation-Reduction; Second Messenger Systems; Signal Transduction; Sphingosine; Thapsigargin