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Ischemic preconditioning preserves connexin 43 phosphorylation during sustained ischemia in pig hearts in vivo
Author(s) -
Schulz Rainer,
Gres Petra,
Skyschally Andreas,
Duschin Alexej,
Belosjorow Sergej,
Konietzka Ina,
Heusch Gerd
Publication year - 2003
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/fj.02-0975fje
Subject(s) - connexin , phosphorylation , ischemia , ischemic preconditioning , kinase , p38 mitogen activated protein kinases , in vivo , chemistry , gap junction , protein kinase a , protein kinase c , microbiology and biotechnology , pharmacology , medicine , intracellular , biochemistry , biology
During myocardial ischemia, connexin 43 (Cx43) is dephosphorylated in vitro, and the subsequent opening of gap junctions formed by two opposing Cx43 hexamers was suggested to propagate ischemia/reperfusion injury. Reduction of infarct size (IS) by ischemic preconditioning (IP) involves activation of protein kinase C (PKC) and p38 mitogen activated protein kinase (MAPK), both of which can phosphorylate Cx43. We now studied in anesthetized pigs whether IP impacts on Cx43 phosphorylation by measuring the density of non‐phosphorylated and total Cx43 (confocal laser) during normoperfusion and 90‐min ischemia in non‐preconditioned and preconditioned hearts. Co‐localization of PKCα, p38MAPKα, and p38MAPKβ with Cx43 and the activity of p38MAPK were assessed. IP by 10 min ischemia and 15 min reperfusion reduced IS. Non‐phosphorylated Cx43 remained unchanged during ischemia in preconditioned hearts, while it increased from 35±3 to 75±8 AU ( P <0.05) in non‐preconditioned hearts. Co‐localization of PKCα, p38MAPKα, and p38MAPKβ with Cx43 during ischemia increased only in preconditioned hearts. While the ischemia‐induced increase in p38MAPKα activity was comparable in preconditioned and non‐preconditioned hearts, p38MAPKβ activity was increased only in preconditioned hearts. Blockade of p38MAPK by SB203580 attenuated the IS‐reduction and the increased p38MAPK‐Cx43 co‐localization by IP. We conclude that IP increases co‐localization of protein kinases with Cx43 and preserves phosphorylation of Cx43 during ischemia.