Integrative erectile biology: the role of signal transduction and cell-to-cell communication in coordinating corporal smooth muscle tone and penile erection.

The contractility of corporal smooth muscle plays a critical role in the entire erectile process in man. Moreover, in the absence of severe vascular disease, or congenital or other structural abnormalities/malformations, relaxation of the corporal smooth muscle is both necessary and sufficient to elicit a sustained erection. As such, understanding the initiation, maintenance and modulation of corporal smooth muscle tone is an absolute prerequisite to the improved understanding, diagnosis and treatment of erectile dysfunction. Despite this fact, identification of both the precise mechanistic basis by which endogenous and exogenous vasomodulators exert their effects on individual corporal smooth muscle cells, and moreover, the process by which these signals are spread among the diverse array of parenchymal cells in the paired corpora, remains somewhat of a physiological enigma. Therefore, the goal of this report is two-fold: first, to review current knowledge of the regulation of corporal smooth muscle tone at the cellular and molecular level; and second, to outline a cogent explanation for the rapid and syncytial integration of the effects of diverse stimuli among corporal smooth muscle cells in the human penis.