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Rho‐kinase inhibition suppresses bladder hyperactivity in spontaneously hypertensive rats
Author(s) -
Rajasekaran Mahadevan,
Wilkes Nathan,
Kuntz Steven,
E. Albo Michael
Publication year - 2005
Publication title -
neurourology and urodynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 90
eISSN - 1520-6777
pISSN - 0733-2467
DOI - 10.1002/nau.20122
Subject(s) - rhoa , medicine , rho associated protein kinase , spontaneously hypertensive rat , endocrinology , blood pressure , rho kinase inhibitor , urology , kinase , signal transduction , microbiology and biotechnology , biology
Aims Spontaneously hypertensive rats (SHR) exhibit overactive bladder (OAB) symptoms and have an up‐regulated calcium sensitizing RhoA/Rho‐kinase pathway in their vascular smooth muscle tissues. This study examined the role of RhoA/Rho‐kinase pathway in bladder hyperactivity by evaluating the effect of a specific Rho‐kinase inhibitor (Y‐27632) on SHR bladder function. Methods Adult male SHR (n = 9) and their normotensive controls (Wistar–Kyoto; WKY) (n = 8) were anesthetized and the carotid artery cannulated for blood pressure monitoring. A catheter was fixed into the bladder dome and connected to a pressure transducer and an infusion pump. After equilibration, systemic and bladder pressure were recorded. Continuous filling cystometrograms (CMGs) were performed and threshold pressure (TP), peak pressure (PP), and number of voids and non‐voiding contractions (NVCs) per unit time recorded. Each SHR then received Y‐27632, 10 μmol intra‐arterially. After 10 min, CMG was repeated and the same measurements recorded. Bladder tissues were evaluated immunohistochemically (IHC) for RhoA protein expression. Results SHR exhibited significantly higher number of voids and NVCs than normotensive WKY rats ( P < 0.05). In SHR, Y‐27362 administration significantly decreased the number of voids (29%, from 0.83 ± 0.3 to 0.63 ± 0.17 voids/min) and NVCs (61%, from 1.8 ± 0.54 to 0.64 ± 0.167 NVC/min). IHC showed significantly higher RhoA protein expression in SHR bladder tissues. Conclusions Overexpression of RhoA may play a role in hypertension‐related OAB. Inhibition of Rho‐kinase activity with Y‐27632 produced a significant suppression of bladder overactivity. Identification of Rho‐kinase isoforms that are bladder‐tissue specific and their selective inhibitors may help to disassociate the unwanted hypotensive effects of this approach. © 2005 Wiley‐Liss, Inc.