Cardioprotective effects of Ilex paraguariensis extract: evidence for a nitric oxide-dependent mechanism

Aim To examine the effects of an Ilex paraguariensis (Ip) extract on postischemic alterations derived from 20 min of global ischemia and 30 min of reperfusion. Methods Isolated rat hearts were treated 10 min before ischemia and the first 10 min of reperfusion with Ip 30 μg/ml. In other hearts, chelerythrine (1 μM), a protein kinase C blocker, or lG–nitro l-arginine methyl ester (l-NAME), a nitric oxide synthase inhibitor, were administered prior to Ip infusion. Left ventricular developed pressure (LVDP), +dP/dtmax, −dP/dtmax, and left ventricular end diastolic pressure (LVEDP) were used to assess myocardial function. Thiobarbituric acid reactive substances (TBARS) were measured. Results Ip treatment produced an improvement of postichemic recovery (LVDP=96±8%; +dP/dtmax=95±10%; −dP/dtmax=90±12% vs. 57±6%, 53±6% and 57±8%, respectively, in untreated hearts) and an attenuation of the increase of LVEDP and TBARS content. Chelerythrine did not modify and l-NAME abolished the protection induced by Ip. Conclusions These data are the first demonstration that Ip extract attenuates the myocardial dysfunction provoked by ischemia and reperfusion and that this cardioprotection involves a diminution of oxidative damage through a nitric oxide-dependent mechanism.