Immunohistochemistry of connexin43 and zonula occludens-1 in the myocardium as markers of early ischemia in autopsy material.

Immunohistochemistry of the terminal complement complex (C5b-9) and fibronectin (FN) is useful to detect myocardial ischemia preceding necrosis in the postmortem diagnosis of sudden cardiac death. The present immunohistochemical study examined connexin43 (Cx43) and zonula occludens-1 (ZO-1) as markers of early myocardial ischemia in addition to the above-mentioned markers, using forensic autopsy cases of acute deaths due to myocardial infarction (MI, n=15) and acute ischemic heart disease (AIHD) without apparent myocardial necrosis (n=8), compared with those of acute mechanical asphyxiation (As, n=24) and drowning (D, n=10) as controls. Immunopositivities of each marker in the myocardium were semi-quantitatively graded by scoring. ZO-1, C5b-9 and FN were detected in the myocardial cytoplasm, whereas Cx43 and non-phosphorylated (np) Cx43 showed varied localizations at the intercalated disc, in the cytoplasm and along the lateral cell border. ZO-1 and FN showed a tendency to be detected more intensely in MI and IHD than in As and D. C5b-9 showed specific staining at the site of ischemia in MI (n=10/15) and AIHD (n=6/8), while the distribution of npCx43 was different in most cases of MI (n=14/15) and AIHD (n=5/8), compared with As and D; npCx43 positivity score was higher in the cytoplasm than at the intercalated disc, indicating redistribution due to myocardial ischemia. Such findings were detected in a few cases of As (n=3/24). These findings suggest that the combination of npCx43 and C5b-9 immunohistochemistry is useful for detecting early lesions of myocardial ischemia in sudden cardiac death.