We investigated the effects of efferent VS on myocardial ischemic injury with in vivo and in vitro mouse models. In in vivo hearts VS significantly increased the expression of TNF-α both at the messenger and protein level after 3-hours of myocardial ischemia. In the in vitro studies ACh treatment before hypoxia, induced a significant upregulation of TNF-α compared to the untreated cardiomyocytes. Immunofluorescence analysis confirmed the synthesis of TNF-α by cardiomyocytes both in vivo and in vitro. VS also significantly reduced the myocardial infarct size (23.9 ± 5.7 % vs. 56 ± 1.9 % ) and activated the cell survival Akt cascade system. Further, ACh upregulated the cell survival TNFR2 expression, while downregulating the cell destructive TNF receptor 1 (TNFR1) expression. These results were confirmed using the TNF receptors deficient mice, where the VS mediated protection was lost both in vivo and in vitro in TNFR2 (TNFR2-/-) and TNF receptors double knock out (TNFR1-/-2-/-) mice.
VS and ACh protects the heart against acute ischemia or hypoxic injury by differentially regulating the TNF receptor subtypes.