Objective To apply wirelss telemetry technology to evaluation on the effect of circadian administration of melatonin on blood pressure and serum endothelin (ET) in spontaneously hypertensive rats (SHR),amd explore the antihypertensive mechanism of melatonin.
Methods Melatonin solution (10 mg/kg) were intraperatoneally injected into six 20-week-old SHRrats one hour before the peak and the trough of systolic blood pressure (SBP) rhythm respectively,and systolic,diastolic (DBP),and mean blood pressures (MBP) were continuously monitored by wirelss telemetry technology for comparison.Blood samples were takento measure nitric oxide (NO) and ET at 0,1,2,and 3 h after the melatonin injection for before-and-after comparison.
Results After melatonin treatment for 2 h,the peak and the trough injection groups were decreased by 11.56% and 10.45% for SBP,12.66% and 16.63% for DBP,12.02% and 12.88% for MBP,respectively.After melatonin treatment for 1 h,the levels of NO of the two groups increased by 55.44% and 79.1%,but the levels of ET decreasded by 14.22% and 29.04%.
Conclusion Melatonin treatment could result in a lower blood pressure in the SHR rats,partially due to mediation of up-regulated NO and down-regulated ET levelsgroup
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