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The immunohistochemical detection of dityrosine, troponins I (cTNI) and T (cTnT), and connexin 43 has been proposed as a tool for the diagnosis of myocardial infarction with short survival times. Results of clinical and experimental studies reveal that gender and/or ischemic preconditioning of the heart may have an influence on severity and magnitude of myocardial infarction. To clarify the question, if the above-mentioned markers are influenced by sex or ischemic preconditioning, experiments on isolated rat hearts using the Langendorff technique were performed. Using the hearts of 12 male and 12 female Wistar rats a local ischemia was induced through ligation of the left coronary artery. Furthermore, 12 male rat hearts underwent ischemic preconditioning of the heart by stopping the perfusion of the whole heart for 30 min and subsequently reperfusing the heart for another 60 min, before inducing local ischemia. The perfusion time after ligation varied from 10 to 60 min. A control group was comprised out of 6 male and 2 female rat hearts. These were placed in the Langendorff system for 60 min without further manipulation or received ischemic preconditioning without subsequent local ischemia or were excised without being mounted on the Langendorff system at all. All hearts were fixed in formalin and stained immunohistochemically. Depletion of the marker cTnT appeared to be less in females when compared to male hearts, for all other markers tested, no apparent difference in staining results were seen when comparing male and female rat hearts. Male rat hearts with ischemic preconditioning showed no difference compared to male rat hearts without ischemic preconditioning when stained fort dityrosine. Connexin 43 staining was less pronounced in hearts with ischemic preconditioning, whereas cTnI as well as cTnT depletion was more pronounced in preconditioned hearts. The presented findings indicate to some extent the vulnerability of the investigated markers for the influencing factors tested. [ABSTRACT FROM AUTHOR]

Myocardial infarctions go along with biomechanical stress, i.e. stretching of muscle fibres, and the expression of certain marker molecules. We tested if two of those markers, endothelin-1 (ET-1) and growth differentiation factor 15 (GDF-15), can be used as immunohistochemical markers for myocardial ischaemia/infarctions. The study included experiments with an animal model, the isolated perfused Langendorff heart, as well as the investigation of human tissue samples drawn during autopsies. The overall picture of our results showed that GDF-15 is very sensitive and expressed very fast, not only as a consequence of ischaemia/infarctions, but also under other circumstances. Even an expression only caused by agony had to be discussed. ET-1, on the other hand, was less sensitive but only positive in those human cases with ischaemia/infarction that also showed typical alterations in conventional histology. Therefore, both markers did not proof to be a suitable diagnostic tool for myocardial infarctions. However, positive staining for ET-1 was also seen in rats’ hearts that suffered from arrhythmias after electric shock and in the myocardium of the right ventricle in human control cases in which a right heart failure has to be discussed. Thus, especially ET-1 should be subject of further studies that focus on these pathologies. [ABSTRACT FROM AUTHOR]