The Effects of LCitrulline 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 Lcitrulline pretreatment on the tension of isolated rat aortic tissues precontracted by different vasoconstrictors. METHODS: Sixteen male Wistar rats (300350g) 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 Lcitrulline (CIT) i.p. for 7days. Rats were euthanized, their thoracic aortas were immediately separated and placed into a petridish containing cold KerebsHenseleit 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 2×106 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 LNAME as a pharmacological probe. RESULTS: The pretreatment of rats by CIT significantly (P lt;0.05) reduced the plateau contraction induced by Phe. CIT also significantly (P lt;0.01) decreased the contraction induced by KCl and LNAME+Phe. However, cumulative addition of ACh significantly (P lt;0.001) decreased the vasoconstriction induced by Phe but not by KCl and LNAME+Phe in both control and CITtreated group. CONCLUSIONS: It suggests that, CIT can reduce the rat aorta vasoconstriction through releasing NO.