ABSTRACT
PURPOSE: Relaxation of the penile cavernosum smooth muscle is a critical event in erection. Artemisia iwaymogi(AI) is a perennial herb growing in Korea. The aerial parts have been used in folk medicine. Bioassay-guided fractionation of an H2O extract of AI has furnished an inhibitory substance (PCLS-2). We investigated compound extracted in the rabbit corporal cavernosum smooth muscle. MATERIALS AND METHODS: Bioassay-guided fractionation of an H2O extract was used. A strip of rabbit corpus cavernosum was mounted in an organ chamber to measure the isometric tension. PCLS-2 compound induced relaxations were evaluated by in vitro study using muscarinic receptor blocker atropine (ATR), cyclo-oxygenase inhibitor indomethacin, nitric oxide synthase (NOS) ihibitor Nitro-L Arginine-Methyl Ester (NAME), guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin 1-one (ODQ), intrinsic neurotransmission inhibitor tetrodotoxin (TTX), or/and potassium channel blockers. RESULTS: PCLS-2 showed relaxation in a dose-dependent manner. Atropine, Indomethacin, NAME, ODQ, TTX, glibenclamide, tetraethylammonium, 4-aminopyridine, charybdotoxin, or apamin did not inhibit the relaxation induced by PCLS-2 compound. CONCLUSIONS: The present results suggest that the PCL-2 compound has effect of relaxation of corpus cavernosum smooth muscle and the relaxation was not involved muscarinic receptor, nitric oxide, prostaglandin, potassium channels and intrinsic neurotransmission. Other mechanisms may by involved in the PCLS-2 induced relaxation in the rabbit corpus cavernosum smooth muscle.
Subject(s)
4-Aminopyridine , Apamin , Artemisia , Atropine , Charybdotoxin , Glyburide , Guanylate Cyclase , Indomethacin , Korea , Medicine, Traditional , Muscle, Smooth , Nitric Oxide , Nitric Oxide Synthase , Potassium Channel Blockers , Potassium Channels , Prostaglandin-Endoperoxide Synthases , Receptors, Muscarinic , Relaxation , Synaptic Transmission , Tetraethylammonium , TetrodotoxinABSTRACT
PURPOSE: Angiotensin(ANG) II regulates tone of penile smooth muscle for erection. ANG III is a product converted from ANG II by aminopeptidase A. The effects of ANG III have not been clarified in the penile corpus cavernosum. The purpose of the present experiment was to determine whether the ANG III has regulatory function in the control of rabbit corpus cavernosum smooth muscle tone. MATERIALS AND METHODS: A strip of rabbit corpus cavernosum was mounted in an organ chamber to measure the isometric tension. We compared the effects of ANG III(10-7M to 10-5M), ANG II(10-8M to 10-6M) and ANG I(10-7M to 10-5M) on the contractility of the corpus cavernosum smooth muscle. RESULTS: ANG III, ANG II, and ANG I contracted corpus cavernosum smooth muscle strips dose-dependently. The contraction of smooth muscle induced by ANG III was 10 fold less by ANG II. Contractile response to ANG III was not attenuated by captopril(angiotensin converting enzyme inhibitor). Contractile response to ANG III was significantly inhibited by Dup 753 of 10-7M(type 1 specific ANG II receptor inhibitor) but not inhibited by PD 123,319 of 10-6M(type 2 specific ANG II inhibitor). CONCLUSIONS: The present results suggest that ANG III is involved in the regulation of corpus cavernosum smooth muscle tone, and contractile effect to ANG III produced via activation of type 1 ANG II (AT1) receptor. The rank order of potency of contraction was as follows, ANG II>ANG IIIANG I.