[Cyclic GMP mimicks potentiation effect of the nootropic agent vinpocetine on the high threshold A-current in the mollusk neurons].
Institute of Brain Research, Moscow, Russia.Rossiĭskii fiziologicheskiĭ zhurnal imeni I.M. Sechenova / Rossiĭskaia akademiia nauk 09/1998; 84(8):741-6.
High-threshold transient K+ current (IAht) was recorded using a two-microelectrode voltage clamp technique in isolated neurons of the land snail. Effect of the nootropic drug vinpocetine on this current was studied and compared with cyclic nucleotides. The drug either enhanced or left unaltered the IAht, and dibutyryl cyclic GMP (dcGMP) imitated the effect. These two effects were not additive. Dibutyryl cyclic AMP did not imitate, the vinpocetine effect and decreased the amplitude of the IAht. The findings suggest that the cGMP mediated the vinpocetine effect on the Iaht.
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ABSTRACT: Double sucrose gap experiments were carried out to study the effect of phosphodiesterase inhibitors and penetrating analogs of cyclic nucleotides on action potential and contraction of guinea pig ureteral smooth muscle cells. 3-Isobutyl-1-methylxanthine (10 microM) and dibutyryl-cAMP (20 microM) shortened the plateau of action potential and inhibited contraction of smooth muscle cells by increasing potassium permeability of their membrane. Vinpocetine (1 microM) and dibutyryl-cAMP (100 microM) strengthened contraction of smooth muscle cells and shortened action potentials by decreasing sodium permeability of their membrane.
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