Metabolic responses of rabbit corpus cavernosum tissue to various forms of stimulation

The present study was designed to investigate the effect of various forms of stimulation on the levels of high energy phosphates (ATP + CP) in the rabbit corpora cavernosa. Prestimulation with the alpha agonist phenylephrine (200 microM) for five minutes caused a significant decrease in both ATP and Creatine phosphate (CP) when compared with control tissue. Field stimulation (64 Hz) of the precontracted tissue induced an immediate decrease in tension by approximately 50%. The level of ATP + CP after field stimulated-relaxation was not significantly different from that from the initial prestimulation. Field stimulation (FS) from basal tone (2 g) caused a contraction and a significant decrease in both ATP and CP. Phentolamine (10 microM) (alpha-adrenergic antagonist) induced a significant decrease in the 2 g basal tension and a significant increase in the intracellular concentrations of both ATP and CP from that of control levels. In summary, the contractile response to both neuronal and pharmacologic stimulation was similar to that of other smooth muscle, producing a decrease in high energy phosphates. Field stimulated relaxation did not change the level of high energy phosphates from that of prestimulated levels. Finally, our data indicates that in the presence of the alpha blocker phentolamine (10 microM), high energy phosphate levels (ATP + CP) increase significantly. This indicates that in the corpus cavernosum, there is significant basal tone that is linked to significant tonic alpha receptor stimulation and is maintained by a net consumption of ATP.