LACK OF EFFECT OF CARBON-MONOXIDE INHIBITOR ON RELAXATION INDUCED BY ELECTRICAL-FIELD STIMULATION IN CORPUS CAVERNOSUM

Carbon monoxide has been proposed as a possible neurotransmitter becau se of its ability to bind to the iron atom of the heme of guanylyl cyc lase, which is similar to that of nitric oxide. To determine whether c arbon monoxide exerts an effect on the penis, strips of rabbit corpus cavernosum were mounted in an organ bath for isometric tension studies and the effect of zinc deuteroporphyrin, an inhibitor of heme oxygena se which metabolizes hemoprotein and releases carbon monoxide, on rela xation induced by electrical field stimulation (neurally mediated) was determined. Also observed was relaxation induced by electrical field stimulation after incubation with atropine and guanethidine to isolate nonadrenergic noncholinergic neurotransmission. Zinc deuteroporphyrin (10(-6) M, 10(-5) M, 10(-4) M and 3 x 10(-4) M) did not affect relaxa tion induced by electrical field stimulation in the absence or presenc e of guanethidine and atropine. Therefore, it appears that carbon mono xide does not contribute to neurally mediated relaxation of the rabbit corpus cavernosum