Regular Article
Role of G Proteins and Modulation of p38 MAPK Activation in the Protection by Nitric Oxide against Ischemia–Reoxygenation Injury

https://doi.org/10.1006/bbrc.2001.5477Get rights and content

Abstract

Protein kinase C (PKC)-mediated regulation of the mitogen-activated protein kinases (MAPK) may play a role in the protection afforded by ischemic preconditioning (PC). Nitric oxide (NO) can influence MAPK activation via interaction with PKC or farnesylation of low-molecular-weight (LMWT) G proteins. However, we have recently reported the mechanism of NO-induced cardioprotection to be a PKC-independent process. Therefore, we investigated the role of LMWT G proteins and MAPK signaling in NO-induced cardioprotection against simulated ischemia–reoxygenation (SI-R) injury. Neonatal rat cardiomyocytes treated for 90 min with the NO donor S-nitroso-N-acetyl-l,l-penicillamine (SNAP) 1 mM were protected against 6 h of SI (hypoxic conditions at 37°C with 20 mM lactate, 16 mM KCl at pH 6.2) and 24 h reoxygenation under normal culture conditions. NO-induced protection was blocked by the G protein inhibitor α-hydroxyfarnesylphosphonic acid (αHFP) 10 μM. We studied the time course of p42/44 and p38 MAPK dual-phosphorylation hourly during SI using phospho-specific antibodies. p38 was phosphorylated during SI and the peak phosphorylation was significantly delayed by SNAP pretreatment. The p38 inhibitor SB203580 1 μM, given during SI, protected against injury. Thus the delay in peak p38 activation may contribute to, rather than be the effect of, NO-induced cardioprotection. We have shown that p38β does not contribute to the total p38 signal in our extracts. Thus there is no detectable β isoform. We conclude that the main isoform present in these cells and thought to be responsible for the observed phenomenon, is the α isoform.

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To whom correspondence should be addressed at Waller Department of Cardiology, St. Marys Hospital, Praed Street, London W2 1NY, United Kingdom. Fax: +44-(0)-20-7886-1763. E-mail: [email protected].

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