[The peripheral analgesic action of the exogenous nitric oxide donor: nitroglycerin. A placebo-controlled study of the transdermal action of nitroglycerin on pain sensitivity in the forearm].

Nitric oxide is a biological mediator. In nervous system it acts like neurotransmitter and also modulate acute inflammation. In the peripheral nervous system it blocks the nociceptive stimulus through an increase in postsynaptic neurone GMPc level. Nitro-vasodilator drugs like nitroglycerin are metabolised in the cell given rise to short lived intermediates, which liberating nitric oxide that activate the guanylate cyclase enzyme, increasing the GMPc in smooth muscle cell. This study show that nitroglycerin produces an analgesic action. The pain sensitivity to pinprick test in forearm with nitroglycerin has shown a decrease in a significative manner against placebo. We speculate that nitroglycerin could have a similar action as endogenous nitric oxide in nervous system.