[Effects of hypoxia/reoxygenation on mitogen-activated protein kinase activity in cultured neonatal rabbit cardiac myocytes].
Cardiomyocytes subjected to brief episode of hypoxia possess a resistance to serious damaging effect exerted by a subsequent long-time hypoxia on these cells, which is called hypoxic preconditioning (PC). The pathway of intracellular signal transduction during hypoxia PC has not yet been validated. On a model of hypoxia/reoxygenation (H/R) of cultured neonatal rabbit cardiomyocytes, the present study is taken to investigate the changes of mitogen-activated protein kinase (MAPK) and ribosomal S6 kinase (S6K) activity. It was found that intracellular total MAPK and nuclear MAPK, after a 15-min period of reoxygenation preceded by a single 60-min period of hypoxia, were increased by 95% and 230%, respectively. Intracellular S6K activity increased by 142% at 30 min of H/R vs the control group (P < 0.01). Phosphatase 1 (PPase 1) inhibitor (ocadaic acid, OA 1 mumol/L) augmented the increase of MAPK and S6K activity induced by H/R. However, tyrosine kinase (Tyr K) inhibitor (genistein), protein kinase C (PKC) inhibitor (H7) and preincubation of cardiomyocytes with PKC activator PMA all reduced MAPK activation by H/R. Protein kinase A (PKA) inhibitor (H89), Ca2+/Calmodulin-dependent protein kinase (PKM) inhibitor (W7) or PPase 2a inhibitor (OA 10 nmol/L) had no significant effect on MAPK and S6K activity. The above results suggested that activation of MAPK and S6K activity during hypoxia/reoxygenation there might require participation of PKC, Tyr K and PPase 1, while PKA, PKM and PPase 2a were not involved.
Yu
W J
WJ
Institute of Cardiovascular Research, Beijing Medical University.
Yao
X H
XH
Liu
X H
XH
Chen
K
K
Niu
D D
DD
Su
J Y
JY
Tang
C S
CS
D000818:Animals; D000831:Animals, Newborn; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D015687:Cell Hypoxia; D002478:Cells, Cultured; D019157:Ischemic Preconditioning, Myocardial; D009206:Myocardium / Q000166:cytology / Q000201:enzymology*; D011817:Rabbits; D019893:Ribosomal Protein S6 Kinases / Q000378:metabolism*
D019893:Ribosomal Protein S6 Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases