the effects of l-citrulline pretreatment on the isometric tension of the isolated perfused rat aorta

Background: the achievement of an effective compound for prevention/treatment of hypertension with fewer complications has been of interest in recent years. objectives: this study aimed to examine the effects of l-citrulline pretreatment on the tension of isolated rat aortic tissues precontracted by different vasoconstrictors. methods: sixteen male wistar rats (300-350g) were randomly divided into two groups of control and test. the control group was injected 1ml distilled water, while the animal in the test group received 200 mg/kg l-citrulline (cit) i.p. for 7days. rats were euthanized, their thoracic aortas were immediately separated and placed into a petridish containing cold kerebs-henseleit solution (khs). the aorta were cleaned of the surrounding tissues and cut into 4 rings in the presence of 95% o2+5% co2. the aortic rings divided into 6 subgroups, were suspended into organ bath containing khs at 37oc. the isolated rings were contracted by 2×10-6 m phenylephrine (phe) and 60mm kcl. when the plateau was reached, a cumulative concentration of acetylcholine (ach) was added into organ bath to induce relaxation. the effects of cit on relaxation and the role of no were tested using l-name as a pharmacological probe. results: the pretreatment of rats by cit significantly (p<0.05) reduced the plateau contraction induced by phe. cit also significantly (p<0.01) decreased the contraction induced by kcl and l-name+phe. however, cumulative addition of ach significantly (p<0.001) decreased the vasoconstriction induced by phe but not by kcl and l-name+phe in both control and cit-treated group. conclusions: it suggests that, cit can reduce the rat aorta vasoconstriction through releasing no.