Cardioprotective effects of a Fructus Aurantii polysaccharide in isoproterenol-induced myocardial ischemic rats.

CALB-3, a purified acidic hetero-polysaccharide isolated from Fructus aurantii, has been shown to exert cardioprotective effects in vitro. Recently, we investigated the protective effects of CALB-3 on myocardial injury and its possible mechanisms of action using a rat model of myocardial ischemia. In this study, a myocardial ischemia model was established via intragastric administration of 2 mg/kg isoproterenol (ISO) to male Sprague-Dawley rats (200-220 g) daily for 3 days. We found that pretreatment with CALB-3 (50, 100, and 200 mg/kg, i.g.) daily for 21 days prevented ISO-induced myocardial damage, including improvement in electrocardiographic parameters, and decrease in serum cardiac enzymes, heart vacuolation, and TUNEL-positive cells. We used western blotting to identify the underlying mechanisms and determine the possible signal pathways involved. We found that CALB-3 pretreatment prevented apoptosis, increased the expression of antioxidant enzymes, and enhanced the binding of Nrf2 to the antioxidant response element. In addition, CALB-3 activated the phosphorylation of PI3K/Akt and ERK to increase the cytoprotective effect. Overall, our results show that CALB-3 is a promising polysaccharide for protecting against myocardial injury induced by ISO.