Involvement of nitric oxide and prostacyclin in the antihypertensive effect of low-molecular-weight procyanidin rich grape seed extract in male spontaneously hypertensive rats

10.1016/j.jff.2013.11.008 The aim of this study was to evaluate the involvement of endothelial-relaxing factors as possible antihypertensive mechanism of low-molecular-weight procyanidin rich grape seed extract (LM-GSPE). Thirty 17¿20-week-old male spontaneously hypertensive rats (SHR) were administered water or 375 mg/kg LM-GSPE by intragastric gavage. One millilitre of saline, 30 mg/kg NG-Nitro-L-arginine methyl ester (L-NAME) or 5 mg/kg indomethacin was administrated intraperitoneally. Systolic blood pressure (SBP) and diastolic blood pres- sure (DBP) were recorded before and 6 h after oral administration. Plasma concentration of 6-keto-prostaglandin F1a (PGF1a) was quantified. In addition, we evaluated the relaxation caused by LM-GSPE in different aorta preparations. The antihypertensive effect of LM-GSPE was completely and partially abolished by L-NAME and indomethacin, respectively. In addi- tion, plasma PGF1a was increased in LM-GSPE-administered rats. Finally, LM-GSPE relaxed the intact aorta preparations but did not relax the endothelium-denuded aorta rings. L- NAME inhibited the relaxation caused by LM-GSPE in the SHR aorta rings, but indometha- cin did not. Therefore, the antihypertensive effect of LM-GSPE in SHR is endothelium dependent, and it could be mediated by changes in endothelium-derived nitric oxide bio- availability. Nevertheless, prostacyclin could also contribute additionally to this effect.