Korean J Androl.  2002 Dec;20(3):137-142.

Physiologic Role of K+ Channels in Relaxation of Rabbit Corpus Cavernosal Tissue

• Lee SI
• Lee SW

Abstract

PURPOSE: Ion channels play key roles in determining smooth muscle tone by setting the membrane potential and allowing Ca2+ influx. Potassium channels may be important in modulating corporal smooth muscle tone. In this study, we investigated the effects of potassium channels in the rabbit corpus cavernosal smooth muscle by blocking them with various agents.
MATERIALS AND METHODS
Strips of rabbit corpus cavernosum were prepared for mounting and isometric tension measurement in an organ bath. On cavernosal strips contracted with phenylephrine (PHE), sodium nitroprusside (SNP) was applied in increasing concentrations from 10(-7)M to 10(-4)M, causing dose-dependent relaxation. The effects of various potassium channel blockers on SNP-induced relaxation were then evaluated by measuring the tension of the cavernosal strips. The potassium channel blockers used were tetraethyl ammonium (TEA), charybdotoxin, gliben clamide, and apamin.
RESULTS
The relaxation responses to SNP of the corporal preparations contracted in response to PHE were significantly attenuated by TEA (10(-2)M) and charybdotoxin (10(-7)M), with no significant difference observed between the two drugs. The SNP-induced relaxation responses were not significantly attenuated by glibenclamide (10(-5)M) or apamin (10(-5)M).
CONCLUSIONS
These results suggest that maxi-K+ channels play an important role in corpus cavernosal relaxation. The KATP channel and small-conductance KCa channel are thought to be unrelated to corpus cavernosal smooth muscle relaxation.

Keyword

K+ channels; Corpus cavernosum smooth muscle; Nitric oxide

MeSH Terms

Ammonium Compounds
Apamin
Baths
Charybdotoxin
Glyburide
Ion Channels
Membrane Potentials
Muscle, Smooth
Nitric Oxide
Nitroprusside
Phenylephrine
Potassium Channel Blockers
Potassium Channels
Relaxation*
Tea
Apamin
Charybdotoxin
Glyburide
Ion Channels
Nitric Oxide
Nitroprusside
Phenylephrine
Potassium Channel Blockers
Potassium Channels
Tea