Summary
The Na+/H+ exchanger plays a key role in pH regulation in the myocardium. It also has a critical role in the damage that occurs to the myocardium during ischemia and reperfusion. Regulation of the Na+/H+ exchanger has not been well studied in the mammalian myocardium. We examined protein kinases responsible for phosphorylation of the Na+/H+ exchanger in the healthy and in the ischemic myocardium. In the healthy myocardium several protein kinases of varying molecular weights phosphorylated the Na+/H+ exchanger. The major NHE1 kinases were of molecular weight 90, 55—50, 44 and 40kDa. We were able to identify p90rsk and ERK as two of the kinases involved in phosphorylation and regulation of the Na+/H+ exchanger. We tested the role of CaM kinase II, protein kinase C, JNK 1/2 and p38 and were unable to demonstrate a direct role in phosphorylation of the Na+/H+ exchanger. Both ischemia and ischemia followed by reperfusion, increased activity of the Na+/H+ exchanger directed protein kinases. The results demonstrate that p90rsk and ERK1/2 are important in regulation of the Na+/H+ exchanger in the healthy and ischemic myocardium. They suggest that upregulation of Na+/H+ exchanger activity could exacerbate the damage that occurs to the myocardium during ischemia and reperfusion.
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Fliegel, L., Karmazyn, M., Moor, A.N. (2003). Regulatory Role of ERK—Dependent Pathways in Activity of the Na+/H+ Exchanger in the Healthy and Ischemic Myocardium. In: Dhalla, N.S., Takeda, N., Singh, M., Lukas, A. (eds) Myocardial Ischemia and Preconditioning. Progress in Experimental Cardiology, vol 6. Springer, Boston, MA. https://doi.org/10.1007/978-1-4615-0355-2_3
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DOI: https://doi.org/10.1007/978-1-4615-0355-2_3
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