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Abstract-The effects of propranolol on lipid metabolism were studied in spon taneously hypertensive rats (SHR).Male SHR and corresponding Wistar Kyoto rats (WKY) were used at 5 weeks of age. The SHR were given 10 mg/kg/day of dl-propranolol•HCI by gavage for 10 weeks. Body weight gain in untreated SHR and propranolol-treated SHR (SHR-P) groups were low, as compared with those of the WKY group.Total cholesterol, phospholipid and total lipid of the serum and liver in the SHR-P group were higher than in the SHR group.In the early weeks of treatment, serum triglyceride and non-esterified fatty acid levels in the SHR-P group were slightly lower than those in the SHR group.Aortic lipid levels in the SHR-P group were lower than those in the SHR group.During the later weeks of treatment, blood glucose level in the SHR-P group was higher than in the SHR group.The serum immunoreactive insulin value in the SHR-P group was slightly lower than in the SHR group.These results may suggest that propranolol inhibits hormone-sensitive lipase activity in the early weeks of treatment and influences cholesterol biosynthesis and/or catabolism.

Abstract-Wehave investigated

Abstract-The relationship between the onset of hypertension and changes in monoamine oxidase (MAO) activity in the brains and hearts of spontaneously hypertensive rats (SHR) were studied. After 7-weeks-old, blood pressure of SHR increased rapidly and reached a level of 170 to 180 mmHg; but following 4 weeks of propranolol treatment (10 mg/kg/day), blood pressure decreased significantly compared to that of untreated SHR. Heart/body weights ratio of SHR was higher than that of normotensive Wistar Kyoto rats (WKY). MAO activities in the brain stem, the medulla oblongata and pons of the SHR were significantly higher than those in WKY at 7 weeks of age, and MAO activity in the brain stem of the propranolol-treated SHR was significantly lower than that in the untreated SHR. Propranolol inhibited MAO activity in brain tissue in vitro, and the 150 values of propranolol were identical (1 X10-4 M) in SHR and WKY. In both the WKY strain and the SHR, the Vmax values of heart MAO increased with age, and the Vmax values of SHR were twice those of WKY. Km values for tyramine of heart MAO in WKY and SHR were approx. 100 PM and 140 ,iM, respectively; however, these values were not age-dependent. It was concluded that an increase in MAO activity in SHR brain stem may trigger a reduction in noradrenaline content and that propranolol may be responsible for its restoration, thus reducing peripheral sympathetic activity; moreover, the increase in MAO activity in the hearts of SHR may be of genetic origin.

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