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Inhibition of RhoA/Rho kinase pathway is involved in the beneficial effect of sildenafil on pulmonary hypertension
Author(s) -
Guilluy Christophe,
Sauzeau Vincent,
RolliDerkinderen Malvyne,
Guérin Patrice,
Sagan Christine,
Pacaud Pierre,
Loirand Gervaise
Publication year - 2005
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1038/sj.bjp.0706408
Subject(s) - rhoa , sildenafil , fasudil , rho associated protein kinase , myosin light chain phosphatase , pulmonary hypertension , rho kinase inhibitor , myosin light chain kinase , protein kinase a , phosphorylation , pharmacology , kinase , pulmonary artery , endocrinology , medicine , cgmp specific phosphodiesterase type 5 , chemistry , signal transduction , biochemistry
Inhibition of the type 5 phosphodiesterase and inhibition of Rho kinase are both effective in reducing pulmonary hypertension (PH). Here we investigate whether Rho kinase inhibition is involved in the beneficial effect of the type 5 phosphodiesterase inhibitor sildenafil on PH. Chronic hypoxia‐induced PH in rats is associated with an increase in RhoA activity in pulmonary artery that was maximal after 2 days (10.7±0.9‐fold increase, n =6, P <0.001). The activity of Rho kinase assessed by measuring the level of myosin phosphatase target subunit 1 (MYPT1) phosphorylation was also increased (5.7±0.8‐fold over control, n =8). Chronic fasudil (30 mg kg −1 day −1 ; 14 days) and sildenafil (25 mg kg −1 day −1 ; 14 days) treatments reduced PH and pulmonary cardiovascular remodelling, and inhibited the MYPT1 phosphorylation in pulmonary artery from hypoxic rats by 82.3±3% ( n =4) and by 76.6±2% ( n =4), respectively. The inhibitory effect of sildenafil (10 μ M ) on MYPT1 phosphorylation was demonstrated by the loss of actin stress fibres in vascular smooth muscle cells. However, in vitro kinase assays indicated that sildenafil had no direct inhibitory action on Rho kinase activity. Sildenafil treatment induced increased RhoA phosphorylation and association to its cytosolic inhibitory protein, guanine dissociation inhibitor (GDI) in pulmonary artery. We propose that sildenafil inhibits RhoA/Rho kinase‐dependent functions in pulmonary artery through enhanced RhoA phosphorylation and cytosolic sequestration by GDI. The inhibition of intracellular events downstream of RhoA thus participates in the beneficial effect of sildenafil on PH.British Journal of Pharmacology (2005) 146 , 1010–1018. doi: 10.1038/sj.bjp.0706408