GSK-3β at the crossroads in the signalling of heart preconditioning: implication of mTOR and Wnt pathways.

Aims: Ischaemic preconditioning (IPC) protects the heart against prolonged lethal ischaemia through a signalling cascade involving Akt, glycogen synthase kinase-3β (GSK-3β), and mitochondrial ATP-sensitive potassium channels (mitoK(ATP)). We previously demonstrated the involvement of the Wnt pathway in IPC in vivo via GSK-3β. A downstream target might be mammalian target of rapamycin (mTOR) since Wnt can impair tuberous sclerosis complex-2 (TSC2) phosphorylation by inhibiting GSK-3β.

Quantitative analysis of function and perfusion during dobutamine stress in the detection of coronary stenoses: two-dimensional strain and contrast echocardiography investigations.

Background: The recent development of accurate methods to measure two-dimensional strain during dobutamine stress echocardiography has reactivated the debate as to the respective value of myocardial perfusion versus myocardial function assessment in detecting coronary stenoses. The aim of our study was to compare the effects of progressive coronary constrictions on two-dimensional strain and myocardial contrast echocardiography parameters during stress conditions.

Methods: Nine open-chest pigs were studied in the setting of various degrees of coronary constrictions.

Effect of diazoxide on flavoprotein oxidation and reactive oxygen species generation during ischemia-reperfusion: a study on Langendorff-perfused rat hearts using optic fibers.

This study analyzed the oxidant generation during ischemia-reperfusion protocols of Langendorff-perfused rat hearts, preconditioned with a mitochondrial ATP-sensitive potassium channel (mitoK(ATP)) opener (i.e., diazoxide).

Experimental validation of circumferential, longitudinal, and radial 2-dimensional strain during dobutamine stress echocardiography in ischemic conditions.

Objectives: The aim of this study was to assess and validate 2-dimensional (2D) strain for the detection of ischemia during dobutamine stress echocardiography (DSE).

Background: Evaluation of abnormalities of left ventricular (LV) function from wall thickening during DSE is unsatisfactory and requires a high level of expertise.

Methods: In 10 open-chest anesthetized pigs, myocardial deformation was studied before and during dobutamine infusion, under control and ischemic conditions produced by various degrees of coronary artery constriction: 2 of nonflow-limiting stenoses (NFLS) of increasing severity reducing left anterior descending artery hyperemic flow by 40% and 70% and 2 flow-limiting stenoses (FLS) reducing resting coronary flow by 25% and 50%.

Sarcoplasmic ATP-sensitive potassium channel blocker HMR1098 protects the ischemic heart: implication of calcium, complex I, reactive oxygen species and mitochondrial ATP-sensitive potassium channel.

The aim of this study was to investigate the effects of HMR1098, a selective blocker of sarcolemmal ATP-sensitive potassium channel (sarcK(ATP)), in Langendorff-perfused rat hearts submitted to ischemia and reperfusion. The recovery of heart hemodynamic and mitochondrial function, studied on skinned fibers, was analyzed after 30-min global ischemia followed by 20-min reperfusion. Infarct size was quantified on a regional ischemia model after 2-h reperfusion.