Relaxation Responses of Isolated Rabbit Seminal Vesicle to Polyamines / 대한비뇨기과학회지

PURPOSE: This study was designed to investigate the effects of polyamines on rabbit seminal vesicular contractility. MATERIALS AND METHODS: The polyamines; putrescine, spermidine and spermine, were added to deepithelized and precontracted seminal vesicle strips, with either 10 4M norepinephrine (NE), 10 4M acetylcholine (ACh) or 70mM KCl, in organ chambers to obtain cumulative concentration response curves. A whole cell mode patch clamp study was also performed to observe the effects of the polyamines on the L-type calcium channel activities. RESULTS: The polyamines elicited concentration-dependent relaxations of the precontracted strips with the NE, ACh and KCl. The spermine showed the most potent relaxation response. Both extracellular and intracellular application of the spermine decreased the L-type calcium channel currents. CONCLUSIONS: Spermine more potently inhibited the seminal vesicle contraction than putrescine or spermidine, which suggests the polyamines may play a role in maintaining the basal tonicity of seminal vesicle in a flaccid state. The spermine-induced relaxation response seems to be related with an inhibition of the L-type calcium channel activities.

Contraction and Relaxation Responses of Isolated Rabbit Seminal Vesicle to Selective beta Subtypes-adrenoceptor Agonists and Antagonists / 대한비뇨기과학회지

PURPOSE: This study was aimed at investigating the role of betaadrenoceptor subtypes in mediating the relaxation and contraction of seminal vesicles in rabbits. MATERIALS AND METHODS: Relaxation or contractile responses of epithelium- removed muscle strips of a rabbit seminal vesicle, which were precontracted with 10-5M norepinephrine, to selective betasubtypes-adrenoceptor agonists were observed in an organ bath. The contractile responses induced by isoproterenol were also observed after application of selective antagonists. RESULTS: Isoproterenol showed a concentration-dependent contractile response, but the contractility was weaker than those with phenylephrine and norepinephrine. The betaselective-agonists(xamoterol for beta, clenbuterol for beta and BRL37344 for beta) alone evoked neither contraction nor relaxation. However, the beta- and beta-agonists inhibited the contraction of the precontracted strips with 10-5M norepinephrine, while the beta-agonist enhanced the contraction. The pretreatment with a beta-antagonist(ICI118551) reduced the tension of the strips developed by 10-4M isoproterenol, but the beta-(atenolol) and beta-(SR59230A) antagonists showed no changes in the response. CONCLUSIONS: beta- and beta-adrenoceptors seem to mediate the relaxation of the seminal vesicle, while the beta-adrenoceptor may have a supplementary role in contraction.

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

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.

The Effects of Botulinum Toxin-A on Calcium Channel and KDR Channel of the Detrusor Muscle in Rat Bladder Body / 대한비뇨기과학회지

PURPOSE: Botulium toxin-A (BoTx A) is useful in treating detrusor-sphincter dyssynergia, detrusor hyperreflexia, and refractory overactive bladder. Only the blocking action of acetycholine (ACh) release from nerve endings is the well known aspect of the action mechanism. The aim of this study is to investigate the effects of BoTx A on the detrusor muscle itself. MATERIALS AND METHODS: Sprague-Dawley rats were divided into 3 groups: the control group, the low dose injection group (1unit/ml of BoTx A, 0.5cc), and the high dose injection group (5units/ml of BoTx A, 0.5cc). All rats were either injected with normal saline (control group) or BoTx A (injection groups). Ten days after injection, a strip of the detrusor muscle was harvested. Contraction and relaxation responses of the strips were measured by an isometric force transducer. Contractions were induced by various concentrations of ACh, bethanechol, phenylephrine (PE), high concentrations of potassium (35, 70, 105, 140mM), tetraethylammonium (TEA, 0.1, 1, 10mM), 4-aminopyridine (4-AP, a delayed rectifier K+ antagonist, 0.1, 1, 10mM), and Bay K8644 (a L-type voltage dependent calcium channel opener, 0.1, 1, 10mM). The results were analyzed by ANOVA and the Student's t test. RESULTS: Contractions of the strips were noted when concentrations were above 1mM for TEA and above 0.1mM for 4-AP. A high dose injection as well as a low dose injection of BoTx A had no significant effects on the Ach or bethanechol-induced contractions of the strips compared to the control group. Denervation supersensitivity was not found in the injection groups after the Ach and bethanechol treatments, but the contractility was decreased in high concentrations of potassium (70, 105, 100mM), TEA (10mM), 4-AP (10mM), and Bay K8644 in both the high and low dose injection groups. There was no significant difference in the decrease of contractility between the high and low dose groups with the exception of the Bay K8644 1M treatment. CONCLUSIONS: BoTx seems to have some direct effects on decreasing the contractility of the detrusor muscle by increasing the delayed rectifier K+ channel activity and decreasing the L-type voltage dependent calcium channel activity.