Korean J Androl.  2003 Apr;21(1):32-37.

Role of Rho-Kinase Activity in Angiotensin II-Induced Contraction of Corpus Cavernosum Smooth Muscle in the Rabbit

• Kim MK
• Park JK

Abstract

PURPOSE
RhoA/Rho-kinase regulates vascular tone via a calcium sensitization mechanism. Stimulation of the AT1 receptor by angiotensin (ANG) II activates the Rho A/Rho-kinase signaling pathway. However, its role in corpus cavernosum smooth muscle (PCSM) has not been known.
MATERIALS AND METHODS
Isometric tension measurements were performed in rabbit PCSM using a selective Rho-kinase inhibitor, (+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl) cyclohexanecarboxamide (Y-27632), and a selective myosin light chain kinase (MLCK) inhibitor, 1-(5-iodonaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine hydrochloride (ML7).
RESULTS
Y-27632 significantly attenuated contractions induced by ANG II in a dose-dependent fashion. However, ML7 did not affect the contractile response to ANG II except at high concentration. Y-27632 inhibited contraction in response to phenylephrine (PhE), but ML7 did not. A nitric oxide synthase inhibitor, NG-nitro-L-arginine-methyl ester, did not affect Y-27632-induced relaxation of the strip contracted with PhE.
CONCLUSIONS
A G-protein-coupled increase in myofilament Ca2+ sensitivity, mediated through the RhoA/Rho-kinase signaling pathway, is involved in the regulation of the PCSM tone induced by ANG II. The RhoA/Rho-kinase pathway acts in AGN II-induced contraction independent of the NO pathway.

Keyword

Angiotensin II; Ca2 sensitization; Corpus cavernosum smooth muscle; Myosin light chain kinase; RhoA/Rho-kinase

MeSH Terms

Angiotensin II
Angiotensins*
Calcium
Muscle, Smooth*
Myofibrils
Myosin-Light-Chain Kinase
Nitric Oxide Synthase
Phenylephrine
Relaxation
rho-Associated Kinases*
Angiotensin II
Angiotensins
Calcium
Myosin-Light-Chain Kinase
Nitric Oxide Synthase
Phenylephrine
rho-Associated Kinases