Division of Urology, Harbor-UCLA Medical Center, Torrance 90509, USA.
The neuronal nitric oxide synthase (nNOS) is the main NOS isoform in the urogenital tract catalyzing the synthesis of nitric oxide, the mediator of penile erection and presumably an important factor in the control of urinary voiding. We have cloned from the rat penile corpora cavernosa a cDNA coding for a novel nNOS differing from the cerebellar nNOS by the presence of a 102 nucleotides stretch and other features. This new species is the only nNOS mRNA expressed in the rat penis, urethra, prostate, and skeletal muscle, coexists with the cerebellar nNOS in the pelvic plexus and bladder, and is detectable in the cerebellum. The novel insert is present in human penile RNA and is transcribed from intron 16. The features and distribution of the penile nNOS suggest that it is may be regulated differentially from the cerebellar nNOS.