Korean J Urol.  2004 Aug;45(8):828-833.

An Insulin-induced, Endothelium-dependent Relaxation Mechanism of Normal Rabbit Cavernous Smooth Muscle

• Myung SC
• Han JY
• Lee YS
• Keum EM
• Lee MY
• Kim SC

Abstract

Purpose
Insulin is known to induce relaxation in various vasculatures by increasing the release of nitric oxide or the expression of nitric oxide synthase. However, its action mechanisms on the corpus cavernosum remain to be uncovered. This study aimed to investigate the relaxative responses and the mechanism of normal cavernous smooth muscles to insulin.
Methods
and Materials: Rabbit corpus cavernous tissues were prepared in 2x2x8 mm sized strip for isotonic tension recording. The dose-dependent relaxation responses of norepinephrine (10(-4)M)-precontracted strips to insulin (10(-6)M)were measured. The relaxation responses of NE (10(-4)M)-precontracted strips to insulin (10(-6)M) were measured under low to high glucose concentrations (0, 0.1, 1 and 11mM) in physiological solution. The relaxation responses of the NE-precontracted strips to insulin (10(-6)M) were also observed after endothelial denudation, 30-minute preincubation with L-NAME (5mM) or 30-minute preincubation with indomethacin (10(-4)M).
Results
The cavernosal strips were relaxed by insulin in a dose-dependent manner. The insulin-induced relaxation was dose-dependently increased by glucose. The endothelial denudation or indomethacin pretreatment almost abolished the insulin-induced relaxation, but L-NAME rarely affected the relaxation.
Conclusions
Insulin induces an endothelium-dependent relaxation of rabbit cavernous smooth muscles, which is mostly NO-independent, but seems to be related with prostaglandins or their metabolites.

Keyword

Insulin; Corpus cavernosum; Relaxation

MeSH Terms

Glucose
Indomethacin
Insulin
Muscle, Smooth*
NG-Nitroarginine Methyl Ester
Nitric Oxide
Nitric Oxide Synthase
Norepinephrine
Prostaglandins
Relaxation*
Glucose
Indomethacin
Insulin
NG-Nitroarginine Methyl Ester
Nitric Oxide
Nitric Oxide Synthase
Norepinephrine
Prostaglandins