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

OBJECTIVE(S): 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.