1. We reported recently the cardioprotection conferred by a non-alcoholic extract of Cabernet-Sauvignon red wine (RWE) against alterations derived from ischaemia and reperfusion in normotensive rats. The aim of the present study was to assess the effects of RWE on ischaemia/reperfusion injury in hearts isolated from spontaneously hypertensive rats (SHR). 2. After stabilization, rat isovolumic perfused hearts were exposed to a 20 min global ischaemic period followed by 30 min reperfusion in the absence (ischaemic control (IC) hearts) or presence of RWE infused prior to ischaemia and early in reperfusion. In other hearts, N(G)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase, was administered prior to RWE infusion (L-NAME + RWE). 3. Left ventricular developed pressure (LVDP), dP/dt(max) and left ventricular end-diastolic pressure (LVEDP) were used to assess myocardial function. 4. At the end of reperfusion, LVDP and dP/dt(max) decreased to 47 +/- 9 and 46 +/- 9% of baseline values, respectively, in IC. Treatment with the RWE significantly improved systolic postischaemic recovery (LVDP = 85 +/- 8%; dP/dt(max) = 83 +/- 5%) and attenuated the increase in LVEDP (23 +/- 6 and 53 +/- 8 mmHg in RWE and IC, respectively; P < 0.05). 5. In the L-NAME + RWE group, L-NAME completely abolished the systolic and diastolic protection induced by RWE (LVDP = 44 +/- 13%; dP/dt(max) = 43 +/- 13%; LVEDP = 60 +/- 10 mmHg). 6. These data are the first demonstration that a non-alcoholic extract of Cabernet-Sauvignon red wine protects SHR hearts from systolic and diastolic alterations induced by ischaemia and reperfusion through a nitric oxide-dependent mechanism.