Changes in rat myocardium associated with modulation of ischemic tolerance by diazoxide.

Pretreatment with diazoxide, mitochondrial K(ATP) channel opener, was found to protect the rat heart against ischemia/reperfusion injury. Our aim was also to characterize the effects of diazoxide on the alterations of regulatory myocardial proteins, on mitochondrial ultrastructure, integrity and induction of apoptotic responses. Isolated rat hearts were Langendorff perfused and subjected to index ischemia (II) induced by 25 min global ischemia and 35 min reperfusion.

Differential role of PI3K/Akt pathway in the infarct size limitation and antiarrhythmic protection in the rat heart.

Endogenous cardiac protection against prolonged ischemic insult can be achieved by repeated brief episodes of ischemia (hypoxia) or by cardiac adaptation to various stresses such as chronic hypoxia. Activation of phosphatidylinositol 3-kinase (PI3K)/Akt is involved in antiapoptotic effects, however, it is not clear whether it is required for overall heart salvage including protection against myocardial infarction and arrhythmias. We focussed on the potential common role of PI3K/Akt in anti-infarct protection, in the experimental settings of long-term adaptation to chronic intermittent hypobaric hypoxia (IHH; 8 h/day, 25-30 exposures, in vivo rats) and acute ischemic preconditioning (IP; Langendorff-perfused hearts).

Hypercholesterolemia abrogates an increased resistance of diabetic rat hearts to ischemia-reperfusion injury.

Both, diabetes mellitus (DM) and hypercholesterolemia (HCH) are known as risk factors of ischemic heart disease, however, the effects of experimental DM, as well as of HCH alone, on ischemia/reperfusion-induced myocardial injury are not unequivocal. We have previously demonstrated an enhanced resistance to ischemia-induced arrhythmias in rat hearts in the acute phase of DM. Our objectives were thus to extend our knowledge on how DM in combination with HCH, a model that is relevant to diabetic patients with altered lipid metabolism, may affect the size of myocardial infarction and susceptibility to arrhythmias.

The role of NO in ischemia/reperfusion injury in isolated rat heart.

Unlabelled: Nitric oxide (NO) is an important regulator of myocardial function and vascular tone under physiological conditions. However, its role in the pathological situations, such as myocardial ischemia is not unequivocal, and both positive and negative effects have been demonstrated in different experimental settings including human pathology. The aim of the study was to investigate the role of NO in the rat hearts adapted and non-adapted to ischemia.