Remote Ischemic Preconditioning Prevents Sarcolemmal Associated Protein Proteolysis by Mmp-2 Inhibition

The death of myocytes occurs through different pathways, but a key point in the transition from reversible to irreversible injury is the rupture of the plasma membrane. Three major groups of structural proteins that link the extracellular and intracellular milieus and confer structural stability to the cell membrane are present in cardiac myocytes: the dystrophin-associated protein complex, the vinculin–integrin link, and the spectrin-based submembranous cytoskeleton. The objective was to determine if rIPC preserves membrane-associated cytoskeletal proteins (dystrophin and β-dystroglycan) through the inhibition of metalloproteinase type 2 (MMP-2) activity. A second objective was to describe some of the intracellular signals of the rIPC, that modify mitochondrial function and are activated during early reperfusion. Methods: Isolated rat hearts were subjected to 30 min of global ischemia and 60 min of reperfusion (I/R). rIPC was performed by 3 cycles of ischemia/reperfusion in the lower limb (rIPC). Results: As we expected, rIPC significantly decreased the infarct size. rIPC induced an Akt/GSK-3b phosphorylation and the inhibition of the MPTP opening, improving mitochondrial function, increasing membrane potential, ATP production and respiratory control. I/R induced ONOO - production, which activates MMP-2. This enzyme degrades β-dystroglycan and dystrophin and collaborates to sarcolemmal disruption. Conclusion: rIPC attenuates the breakdown of β-dystroglycan and dystrophin through the inhibition of MMP-2 activity. Furthermore, rIPC activates different intracellular pathway that involves the an Akt/Gsk3b and MPTP pore with preservation of mitochondrial function.