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Relaxant effects of L ‐citrulline in rabbit vascular smooth muscle
Author(s) -
Ruiz E,
Tejerina T
Publication year - 1998
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.0702051
Subject(s) - endothelium , apamin , vascular smooth muscle , vasodilation , citrulline , medicine , endocrinology , zaprinast , chemistry , arginine , nitric oxide , biology , biochemistry , potassium channel , smooth muscle , guanylate cyclase , amino acid
1 Vascular endothelium plays a pivotal role in the control of vascular tone through the release of vasoactive factors such as EDRF (NO). 2 The aim of this study was to investigate whether the addition of exogenous L ‐citrulline, the byproduct of the NO‐synthesis, could relax vascular smooth muscle. 3 L ‐citrulline relaxed both endothelium‐denuded and endothelium‐intact rabbit aortic rings precontracted with noradrenaline 10 −6   M (maximum relaxations induced by L ‐citrulline 10 −8   M were 74.1±5.2% vs 51.3±2.8% in endothelium‐denuded and endothelium‐intact arteries, respectively). 4 This relaxant effect was enhanced by zaprinast (a phosphodiesterase type 5 inhibitor) and inhibited by HS‐142‐1 (a particulate guanylate cyclase inhibitor) and by apamin (a K Ca ‐channel blocker). 5 L ‐citrulline (10 −13 –10 −8   M ) increased cGMP levels in aortic rings (maximum value with L ‐citrulline 10 −8   M was 0.165±0.010 pmol cGMP mg −1 of tissue vs 0.038±0.009 pmol mg −1 of tissue in basal). 6 L ‐citrulline as well as NO were released from endothelial cells in culture stimulated with ACh. The values were 6.50±0.50 μ M  vs 2.30±0.20 μ M (stimulated with ACh and basal respectively) for L ‐citrulline and 4.22±0.10 μ M  vs 0.87±0.26 μ M (stimulated with ACh and basal respectively) for NO. 7 These results suggest that L ‐citrulline could be released together with NO from endothelium and may have actions complementary to those of NO in the control of vascular smooth muscle relaxation.British Journal of Pharmacology (1998) 125 , 186–192; doi: 10.1038/sj.bjp.0702051

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