Related Experiment Video
Updated: Mar 28, 2026

Bladder Smooth Muscle Strip Contractility as a Method to Evaluate Lower Urinary Tract Pharmacology
Published on: August 18, 2014
Agmatine Induces Rat Prostate Relaxation through Activation of Peripheral Imidazoline I2 -Receptors
Liang-Ming Lee1, Chia-Ho Lin1, Hsien-Hui Chung1
1Department of Urology, College of Medicine, Taipei Medical University, Wan-Fang Hospital, Taipei, TaiwanDepartment of Surgery, Chi-Mei Medical Center Liouying, Tainan, TaiwanDepartment of Urology, Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, TaiwanDepartment of Medical Research, Chi-Mei Medical Center, Tainan, TaiwanDepartment of Urology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
Objectives:
The effect of agmatine on prostate contractility as well as the roles of imidazoline receptors and potassium channels in this action were studied using isolated Wistar rat prostate tissue.
Methods:
Rat prostate strips were pre-contracted with 1 µmol/L phenylephrine or 50 mmol/L KCl. The relaxation response to agmatine (1-100 µmol/L) was measured. The effects of imidazoline receptor blockers: efaroxan, BU224, KU14R; ATP-sensitive K(+) channels (KATP ) channel inhibitor: glibenclamide; cyclic AMP (cAMP) phosphodiesterase inhibitor: IBMX; or protein kinase A (PKA) inhibitor: H-89 on the agmatine-induced relaxation were studied.
Results:
Agmatine produced relaxation in prostate strips pre-contracted with phenylephrine or KCl in a dose-dependent manner. This relaxation was significantly reduced by BU224, a selective I2 imidazoline receptor (IR) blocker, but not by I1 or I3 IR blockers (efaroxan, KU14R respectively). Moreover, the agmatine-induced relaxation was attenuated by glibenclamide and H-89, but enhanced by IBMX.
Conclusion:
The results suggest that agmatine causes rat prostate relaxation by activation of the I2 IR, which opens KATP channels through cAMP/PKA pathway.
Related Concept Videos
Direct-Acting Cholinergic Agonists: Pharmacological Actions
Adrenergic Receptors: ɑ Subtype
Adrenaline ≥ Noradrenaline >> Isoprenaline
α-adrenoceptors are further divided into α1 and α2-adrenoceptors.
α1-Adrenoceptors: These receptors are located postsynaptically on the effector organs and cause constriction of smooth muscle mediated by activation of phospholipase...
Antihypertensive Drugs: Vasodilators
Nitric Oxide Signaling Pathway
Adrenergic Agonists: Direct-Acting Agents
These agents can be classified...
Adrenergic Antagonists: Pharmacological Actions of ɑ-Receptor Blockers
α1-blockers: These drugs inhibit α1-adrenoceptors on smooth muscle cells, resulting in vasodilation. This vasodilation lowers blood pressure, making α1-blockers valuable in treating hypertension. Additionally,...

