Testing of Neurotropic Effects of Viagra

Abstract

Using intracellular recording, we studied electrical activity of unidentified neurons of the Helix visceral ganglion under conditions of application of Viagra (sildenafil citrate). Neurotropic effects of Viagra were clearly pronounced at concentrations of 10 -5 and 10 -4 M; they were excitatory and reversible. In the case where the concentration was 10 -3 M, the effect of Viagra was converted into an inhibitory one; some hyperpolarization of the neuronal membrane, a decrease in the amplitude of action potentials (APs), and reduction of their first derivatives reflecting the rates of rise of integral inward and outward currents were observed. In the concentration of 0.5×10 -2 М (5.0 mM), Viagra evoked hyperpolarization of the neuronal membrane by 8 to 10 mV. Against the background of such hyperpolarization, APs were rather rapidly reduced and disappeared; after washing out from the preparation tested, the initial values did not recover. The obtained data allow us to believe that the uncontrolled and excessive use of Viagra can be rather dangerous since it can lead to noticeable functional disturbances in the nervous system.