Reports have shown the antioxidant, hypotensive, hypolipidemic and vasodilatory effects of grape (Vitis vinifera L.) seed extract. We have recently shown the relaxatory effect of grape leaf extract on rat uterus and reduction of frog heart rate and contractility. The aim of the present study was to investigate the relaxant effect of Vitis vinifera leaf hydroalcoholic extract (VLHE) on rat thoracic aorta contractions induced by phenylephrine and KCl and the role of aorta endothelium on this action. Rat aorta was removed and placed in an organ bath containing Krebs-Henseleit solution and aorta contractions were recorded isometrically. The results demonstrate that VLHE (0.125-2 mg/ml) reduces the endothelial intact aorta reconstructed by phenylephrine (1mM) dose-dependently (P<0.0001). Extract induced the same response in endothelial denuded aorta, but in a much lesser extent. The IC50 for both groups were 0.45±0.08 and 1.73±0.23 mg/ml, respectively. However, the contractile responses of these groups were similar. VLHE (0.125-2 mg/ml) reduced the contractions induced by KCl (80 mM) dose-dependently (P<0.0001). The relaxatory effect of VHLE on KCl–induced contractions was less than those evoked by Phenylephrine. Vasorelaxatory effect of VHLE on intact aorta was attenuated by nitric oxide synthase inhibitor (L-NAME, 100mM) and gaunyl cyclase inhibitor (methylene blue, 10mM) significantly, but was unaffected by atropine (1mM). The results suggest that the greatest vasorelaxant effect of VHLE on rat aorta is endothelium-dependent and nitric oxide (NO) and cGMP are mostly responsible but cholinergic receptors are not involved.

Backgrand: In recent years toxic effects of aluminum (Al) have been considered. It has been suggested that aluminum can disturb calcium channel current and also can affect IP3 metabolism. As both of the systems are involved in smooth muscle activity, in this study the effect of high Al in the diet on the contractility of the isolated aorta from rats have been studied. Material and Methods: Aluminum (1620 mg/kg of diet was added to the diet for 40 days. Animals were anesthetized, blood samples were collected for Al measurement and a piece of thoracic aorta was connected to an isometric transducer in an organ bath and the activities of the tissue was recorded in response to different concentrations of Kcl and phenylapherin (Phe). Aluminum was measured by flameless AAS. Results: The result show that the response of aorta from high Al consumed animals to Phe was not significantly different from control animals. However the response to 20 and 50 mmol Kcl of the aorta from high Al consumed animals ( 2.5 ± 2 & 3.1±3) was significantly ( P< 0.05) higher compared to the results from control animals (1.6 ±3 & 2 ± 1). Aluminum concentrations in serum were not significantly different. Conclusion: we can conclude that high aluminum intake in rats although does not lead to high serum Al but can change smooth muscle response of aorta and therefore it appears that toxic effect of this element on vascular system of the subjects must be considered.

Objectives: This study aimed to investigate the vascular effect of geraniol, a monoterpene essential oils that is found in some medicinal plants, in rat thoracic aorta. Methods: The thoracic aorta was isolated, cut into rings, mounted in organ-bath chambers containing Krebs’s solution (37oC, 95%O2 and 5%CO2) and equilibrated in resting tension (2g) for 60 min. Isometric tension was recorded under the treatments with vasoconstrictors, geraniol, and various drugs as pharmacological interventions. The effect of geraniol on the contractions evoked by noradrenaline (10mM) was tested after 20 min pre-incubation of aortic rings with increasing concentrations of geraniol in the bath. In various experiments the endothelium-intact or-denuded aortic rings contracted by 80 mM potassium chloride. When contraction was stable geraniol was applied. Relaxation was expressed as % reduction or reversal of initial contraction induced by vasocative agents. The possible participation of nitric oxide (NO), intracellular cyclic GMP and prostacyclin in the relaxant effects of geraniol, were studied by incubating (for 20 min) some rings with the NO synthase inhibitor N-nitro-L-arginine methyl ester (L-NAME, 200 mM), methylene blue(10 mM) and indomethacin (10mM), respectively. Results: Geraniol in dose dependent manner reduced the contractile response to noradrenalin and relaxed of KCl induced active tone in rat aorta. Relaxant effects of geraniol on the KCl induced contraction was not modified by L-NAME, methylene blue and indomethacin. Conclusion: In conclusion geraniol induced dose dependent relaxation in rat aorta, which was endothelium-independent.

Objective: Diabetes is an important risk factor for cardiovascular events. The great percent of morbidity in patients with diabetes is due to endothelial dysfunction. The present study investigated the effects of hydroalcholic extract of Nigella sativa (N. sativa) on contractile and dilatation response of isolated aorta in streptozotocin (STZ) -induced diabetic rat.Materials and Methods: Rats were divided into six experimental groups (control, untreated STZ-diabetic, and N. sativa hydroalcholic extract or metformin-treated diabetic rats). Treated rats received N. sativa extract (100, 200, and 400 mg/kg) or metformin (300 mg/kg) by gavage, daily for 6 weeks.Isolated rat thoracic rings were mounted in an organ bath system then contractile and dilatation responses induced by phenylephrine (PE), acetylcholine (ACh), potassium chloride (KCl), and sodium nitroprusside (SNP) were evaluated in different situations.Results: The lower concentrations of N. sativa seed extract (DE 100 and DE 200) and metformin significantly reduced the contractile responses to higher concentrations of PE (10-6 - 10-5 M) compared to diabetic group (p<0.05 to p<0.01).The relaxation response to Ach 10-8 M, was increased in DE 200 and metformin groups compared to diabetic group (p<0.05). The relaxation responses to Ach 10-7 - 10-5 M were significantly higher in all treated groups compared to diabetic group (p<0.05 to p<0.001).Conclusion: Chronic administration of N. sativa seed extract has a significant hypoglycemic effect and improves aortic reactivity to vasoconstrictor and vasodilator agents in STZ-induced diabetic rats.