The L-arginine-nitric oxide-cyclic GMP pathway mediates inhibitory nonadrenergic-noncholinergic neurotransmission in the corpus cavernosum of human and rabbit

The objective of this study was to compare the effects of nonadrenergic-noncholinergic (NANC) stimulation and nitric oxide (NO) on isolated strips of corpus cavernosum from human and rabbit penis. Authentic NO and electrical field stimulation (EFS) caused rapid, marked, and transient endothelium-independent relaxation responses associated with tissue cGMP and nitrite (NO2^-) accumulation. Responses to both EFS and NO were enhanced by M&B 22,948 and inhibited by oxyhemoglobin or methylene blue. Responses to EFS were inhibited by NO-synthase inhibitors. The subcellular sites of NO generation after EFS or nitroglycerin compared with acetylcholine were less accessible to added oxyhemoglobin, thus supporting the view that NO is generated in NANC neurons or innervated smooth muscle. NO-synthase from corpus cavernosum is a constitutive cytosolic isoform that is dependent on nicotinamide adenine dinucleotide phosphate and tetrahydrobiopterin and is activated by calcium calmodulin.

Duke Scholars

Author Margaret Bush School of Nursing