Raf-1 kinase regulates smooth muscle contraction in the rat mesenteric arteries.
We investigated the potential role of Raf-1 kinase in mesenteric arterial contraction. Inhibitors of Raf-1 kinase, GW5074, L779450 and ZM 336372 reversed phenylephrine (PE)-induced mesenteric vascular contraction. Studies in vivo in rats showed that GW5074 inhibited PE-induced increase in mean arterial pressure in adult female Sprague-Dawley rats. Isometric tension studies in mesenteric arteries of rats showed that GW5074 did not change the KCl-evoked contraction but significantly inhibited the contractions to PE, 5-HT, U46619, endothelin 1, angiotensin II and phorbol 12, 13-dibutyrate (PDBu). In mesenteric vascular smooth muscle cells (VSMCs), PE stimulated increase in Raf-1 phosphorylation which was inhibited by GW5074. Measurement of [Ca(2+)](i) with Fura-2 showed that GW5074-mediated inhibition of PE-induced contraction was not associated with decreases in [Ca(2+)](i). VSMCs treated with PE exhibited higher levels of the contractile proteins, p-MYPT1 and p-MLC(20), which was inhibited by GW5074. Similarly, PDBu induced increases in phosphorylation of Raf-1, MLC(20) and MYPT1 and this was inhibited by GW5074. However, GW5074 did not have any significant effect on PE/PDBu-induced MEK/ERK activation. The results indicate that Raf-1 kinase plays an important role in the regulation of vascular contractility through regulation of calcium sensitization.
Sathishkumar
Kunju
K
Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Tex. 77555-1062, USA.
Yallampalli
Uma
U
Elkins
Rebekah
R
Yallampalli
Chandra
C
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D005260:Female; D007211:Indoles / Q000494:pharmacology; D008638:Mesenteric Arteries / Q000187:drug effects / Q000502:physiology*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D018994:Myosin Light Chains / Q000378:metabolism; D010636:Phenols / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D054645:Protein Phosphatase 1 / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf / Q000037:antagonists & inhibitors / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D007211:Indoles; D018994:Myosin Light Chains; D010636:Phenols; D010656:Phenylephrine; D015240:Phorbol 12,13-Dibutyrate; D019908:Proto-Oncogene Proteins c-raf; D020929:Mitogen-Activated Protein Kinase Kinases; C499850:Ppp1r12a protein, rat; D054645:Protein Phosphatase 1; C489251:5-iodo-3-((3,5-dibromo-4-hydroxyphenyl)methylene)-2-indolinone; D002118:Calcium