Chronic Propranolol Treatment in Young Spontaneously Hypertensive and Normotensive Rats

Oral treatment with propranolol, 1 or 5 mg/kg per day, was started in young spontaneously hypertensive rats (S.H.R.) 1 week after weaning and continued for 12 weeks. The same doses were administered to age-matched normotensive rats. Propranolol was admixed to a standard laboratory diet in concentrations calculated on the basis of average food consumption. Blood pressure was measured by an indirect method.As compared to control S.H.R., a significantly lower blood pressure was recorded in S.H.R. treated with propranolol, 1 mg/kg, at week 10 and 12 of the treatment and in those treated with 5 mg/kg at weeks 6–12. The heart rate was not consistently affected.The blood pressure of control and treated normotensive rats did not differ significantly with the exception of an elevated blood pressure in both dosage groups at the first reading.The growth of rats was not impaired by propranolol and no morphological organ changes related to the treatment could be detected at the end of the experiment.