Local contributing factors in penile erection are trabecular smooth muscie, endothelium, trabecular fibroelastic components, tunica albuginea and local neuro-control. There are three neuroeffector systems in local neuro-control for penile
erection.
One
is adrenergic system causing contraction and the others are cholinergic and noncholinergic nonadrenergic system causing relaxation of corpus cavernosum under normoxia. The effect of these systems under hypoxic condition however is not fully
understood.
The aims of this study were to detect the pharmacophysiological changes of corporal smooth muscle about 3 local neuroeffector systems under hypoxia in the rabbit and to apply the results of study to the management of the priapism. The strips of
rabbit
corporal tissues were studied for isometric tension measurement under normoxia, hypoxia and cooling condition in the organ chambers. Influence of NG-monomethyl-L-arginine (L-NMMA) and L-arginine to acetylcholine under normoxia and effects of
phenylephrine, norephinephrine, acetylcholine, VIP, endothelin 1, papaverine and KCI on the rabbit corpus cavernosal tissue were monitered under normoxia and hypoxias and changes under cooling condition were observed.
Relaxing effect of acetylcholine under normoxia was suppressed with L-NMMA and this suppression was reversed with L-arginine. Relaxation with acetylcholine and contraction with endothelin 1 were suppressed under hypoxic condition. Contracting
effect of
norepinephrine and phenylephrine was stronger under hypoxia or cooling condition than normoxia or 37℃ condition respectively. Relaxing effect of VIP and papaverine on corpus cavernosa was similar under normoxia or hypoxia. These results suggest
that
endothelium-dependent relaxation by cholinergic and noncholinergic nonadrenergic system and endothelium-dependent contraction by endothelin 1 are suppressed under hypoxic condition. VIP related noncholinergic nonadrenergic relaxation and direct
relaxation effect of papaverine to corporal smooth muscle are preserved under hypoxia. Application of adrenergics and local irrigation with cold saline would be effective in the management of priapism.
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