Premium
Signal pathways regulating hyaluronan secretion into static and cycled synovial joints of rabbits
Author(s) -
Ingram K. R.,
Wann A. K. T.,
Wingate R. M.,
Coleman P. J.,
McHale N.,
Levick J. R.
Publication year - 2009
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2009.175620
Subject(s) - protein kinase c , chemistry , bisindolylmaleimide , endocrinology , secretion , microbiology and biotechnology , protein kinase a , medicine , phospholipase c , kinase , signal transduction , biology , biochemistry
Joint lubrication, synovial fluid conservation and many pathophysiological processes depend on hyaluronan (HA). Intra‐articular HA injection and exercise, which stimulates articular HA production, ameliorate osteoarthritis. We therefore investigated the pathways regulating movement‐stimulated articular HA secretion rate () in vivo. Endogenous HA was removed from the knee joint cavity of anaesthetised rabbits by washout. Joints were then cycled passively or remained static for 5 h, with/without intra‐articular agonist/inhibitor, after which newly secreted HA was harvested for analysis. Movement almost doubled . Similar or larger increases were elicited in static joints by the intra‐articular Ca 2+ ionophore ionomycin, prostaglandin E 2 , cAMP‐raising agents, serine/threonine phosphatase inhibitor and activation of protein kinase C (PKC). PKC‐stimulated secretion was inhibited by the PKC inhibitor bisindolylmaleimide I and inhibitors of the downstream kinases MEK‐ERK (U0126, PD98059). These agents inhibited movement‐stimulated secretion of HA (MSHA) only when the parallel p38 kinase path was simultaneously inhibited by SB203580 (ineffective alone). The phospholipase C inhibitor U73122 almost fully blocked MSHA ( P = 0.001, n = 10), without affecting static . The ENaC channel blocker amiloride inhibited MSHA, whereas other inhibitors of stretch‐activated channels (Gd 3+ , ruthenium red, SKF96365) did not. It is proposed that MSHA may be mediated by PLC activation, leading to activation of parallel PKC–MEK–ERK and p38 kinase pathways.