Effects of Low-dose Morphine on Nitric Oxide Concentration and Angiogenesis in Two-kidney One Clip Hypertensive Rats

OBJECTIVES We investigated the effects of low-dose morphine on nitric oxide (NO) and angiogenesis in two-kidney one clip hypertensive (2K1C) rats. MATERIALS AND METHODS MALE RATS WERE DIVIDED INTO TWO GROUPS: sham-clip operated and 2K1C. Each group subdivided into saline and morphine (3 mg/kg i.p. 8 weeks) groups. Blood pressure, heart rate, plasma renin activity (PRA), NO concentration and murine matrigel angiogenesis were evaluated. RESULTS Morphine had no effects on blood pressures and HR in sham normotensive rats but attenuated diastolic blood pressure (DBP) (P< 0.01) and mean arterial pressure (MAP) (P< 0.01) in 2K1C compared with saline. PRA level was significantly higher in 2K1C compared with sham groups (P< 0.01) but morphine decreased it in 2K1C compared with saline (P< 0.01). After clipping, NO in 2K1C hypertensive rats was decreased (P< 0.01) and morphine increased it compared with saline (P< 0.01). Morphine promoted angiogenesis in both sham (P< 0.01) and 2K1C (P< 0.0001) groups. CONCLUSION Low-dose morphine stimulated angiogenesis in two-kidney one clip hypertensive rats probably via NO pathways.