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KMID : 0358319950360030241
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Korean Journal of Urology
1995 Volume.36 No. 3 p.241 ~ p.246
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Role of Endothelium-derived Relaxing and Hyperpolarizing Factors in the Relaxation of the Corpus Cavernosum
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Abstract
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In has been found that acetylcholine releases at least two different substances from the vascular endothelial cells, i.e., relaxing factor and hyperapolarizing factor. The present study was aimed to investigate whether and to what extent these
factors
are involved in the relaxation of the corpus cavernosum.The corpus cavernosum was isolated from male New Zealand shite rabbits and suspended longitudinally in an organ bath. The corporal strips were precontracted with phenylephrine,
tetraethylammonium
(TEA) or potassium chloride, and their responses to electrical field stimulation (EFS) or exogenously-administered acebylcholine were examined.
EFS caused a frequency-dependent relaxation of the corpus cavernosum precontracted with phenylephrine, which was signficantly inhibited or abolished in the presence of procaine (3.5×10E-4 mol/L) or ouabain (1E-4 mol/L). The corporal preparation
precontracted with TEA also showed a frequency-dependent relaxation. however, the degree of which was lower than that precontracted with phenylephrine. EFS was without a significant effect on the corporal preparation precontracted with KCl
(3×10E2
mol/L). Acethylcholine elicted a concentrationdependent relaxation of the corpus cavernosum. the magnitude of which was significantly diminished in the presence of L-NAME (10E-4 mol/L). The relaxation response to EFS of the corporal preparation
precontracted with phenylephrine was significantly attenuated in the presence of L-NAME (10E-4 mol/L), in which the resicdual relaxation was completely abolished by glibenclamide (10E-5 mol/L). The relaxation of the corpus cavernosum in response
to
EFS
was reversed into a contraction by methylene blue (10E-4 mol/L) or TEA (10E-2 mol/L).
These results suggest aht endothelium-derived relaxing and hyperpolarizing factros released upon neural stimulation mediate the relaxation of the corpus cavernosum. It is also suggested that EDRF activates soluble guanylate cyclase and EDHF does
ATP-sensitive potassium channels.
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