cGMP mediates corpus cavernosum smooth muscle relaxation with altered cross-bridge function
1998; Elsevier BV; Volume: 63; Issue: 3 Linguagem: Inglês
10.1016/s0024-3205(98)00259-8
ISSN1879-0631
AutoresALEX T. CHUANG, John D. Strauss, William D. Steers, Richard A. Murphy,
Tópico(s)Neuroendocrine regulation and behavior
ResumoWe tested the prevailing paradigm that relaxation of corpus cavernosum smooth muscle (CCSM) and penile erection depends upon nitric oxide-induced elevation of myoplasmic cGMP and reduced Ca2+-dependent myosin regulatory light chain phosphorylation levels. This hypothesis invokes a reversal of normal activation pathways. Upon stimulation with 250 μM phenylephrine, phosphorylation of the 20 kD myosin regulatory light chains of rabbit or human CCSM increased approximately 4-fold coincident with contraction. Removal of the agonist was followed by a slow reduction in cross-bridge phosphorylation and force to basal levels. The NO donor, sodium nitroprusside elicited a dose-dependent increase in tissue [cGMP] associated with a rapid relaxation in the continued presence of phenylephrine, although cross-bridge phosphorylation remained significantly elevated. Thus the NO-cGMP inhibitory pathway in CCSM is not simply a reversal of excitatory signal transduction mechanisms. An unidentified mechanism contributes to relaxation by decreasing the rate of cross-bridge recruitment through phosphorylation.
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