Increases in extracellular pH activate the MAPK signalling pathways in a mammalian cardiac experimental model

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Changes in extracellular pH can affect cardiac functions such as contractility. We used the H9c2 cardiac cell line to study the effect of alkalosis on the MAPK signalling pathways activation. Alkalosis was exerted by using the Tyrode's buffers (pH 8.5 or 9.5). Alkalosis at pH 8.5 differentially activated all three MAPKs, whereas at pH 9.5 only JNKs were significantly phosphorylated. It is also noteworthy that MAPKs activation was attenuated by the NHE-1 inhibitor HOE642. Bcl-2 and c-Jun were phosphorylated in response to alkalosis (pH 8.5) and the latter observation was corroborated by the fact that nuclear extract binding at oligonucleotides bearing the AP-1 consensus sequence was enhanced under the same alkaline conditions.