Effect of Different Timing of Administration of Enalapril on Blood Pressure, Plasma Nitric Oxide and Endothelin in Hypertension Rats

Objective To study the effect of different timing of application of enalapril on blood pressure, plasma nitric oxide (NO) and endothelin (ET) in hypertension rats. Methods Tweleve male SD rats were randomly divided into 3 groups. Rats hypertension was induced by N G nitro L arginine methlester(L NMAE), blood pressure (BP) was measured continuously for 24 hours. The obtained data were analyzed by the cosinor software to determine the circadian times of peak, mean and trough of BP. Enalapril (10 mg·kg -1 ·d -1 ) was given daily at corresponding peak, mean, and trough times points for 2 weeks. Blood sample was taken to measure the NO and ET. Results The peak, mean and trough. Blood pressure were decreased by 12.2%, 8 2% and 8 3% respectively after treatment; the level of plasma nitric oxide increased by 62 8%?36 5% and 34 5%; and the plasm endothelin decreased by 6 5%?9 7% and 9 8% respectively Conclusion Enalapril reduced the rat hypertension induced by L NAME; The administration before BP peak time appears to result in greater antihypertensive effect and greater NO release.