Premium
Molecular evidence for the involvement of calcium sensitization in serotonin‐induced cerebrovascular constriction
Author(s) -
ElYazbi Ahmed,
Johnson Rosalyn P.,
Takeya Kosuke,
Walsh Emma J.,
Walsh Michael P.,
Cole William C.
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.931.1
Subject(s) - myosin light chain phosphatase , myosin light chain kinase , vasoconstriction , phosphorylation , protein kinase c , rho associated protein kinase , myosin , sensitization , microbiology and biotechnology , medicine , kinase , endocrinology , biology , chemistry , neuroscience
The mechanisms contributing to serotonin (5‐HT)‐induced vasoconstriction of cerebral arteries are poorly characterized. This is important as abnormalities in control of cerebral blood flow by 5‐HT are implicated in subarachnoid hemorrhage and may be involved in migraine. Force generation by vascular smooth muscle cells depends on the balance of myosin light chain kinase (MLCK) and phosphatase (MLCP) activities that determine the level of myosin light chain (LC 20 ) phosphorylation. Agonists that activate Rho kinase (ROK) and protein kinase C (PKC) can inhibit MLCP by phosphorylation of myosin light chain targeting subunit 1 (MYPT1) and CPI‐17, respectively. This inhibition of MLCP leads to increased phospho‐LC 20 and force generation at constant [Ca 2+ ] i , i.e. Ca 2+ sensitization. Here, we have quantified LC 20 , MYPT1 and CPI‐17 phosphorylation in protein samples derived from pressurized segments of rat middle cerebral arteries using a novel, highly sensitive western blotting method. 5‐HT induced constriction and increased phospho‐LC 20 ; both were reduced by ROK (H1152, 0.3 µM) or PKC (GF109203, 3 µM) inhibition. Phospho‐MYPT1 level was increased by 5‐HT, but not phospho‐CPI‐17. Our data indicate for the first time that Ca 2+ sensitization via ROK‐mediated phosphorylation of MYPT1 resulting in enhanced LC 20 phosphorylation and force generation may contribute to 5‐HT‐induced cerebral vasoconstriction.