Effects of Angiotensin III in Rabbit Corpus Cavernosum Smooth Muscle Contraction: Comparing with Angiotensin I and Angiotensin II / 대한비뇨기과학회지

ABSTRACT

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.