Comparative antihypertensive effects of propranolol and metoprolol in DOC-treated rats.
The effects of chronic twice daily s.c. injections of dlpropranolol, metoprolol and d-propranolol on systolic blood pressure and heart rate were assessed in conscious DOC-saline hypertensive rats. Measurements were taken (tail-cuff) 4 hr after the morning injection and 16-18 hr after the afternoon injection during 11 of 19 consecutive treatment days. Only dl-propranolol and metoprolol at 5 mg/kg lowered blood pressure and heart rate significantly relative to the changes occurring in control saline-injected animals. At the lower dose of 0.2 mg/kg, both agents tended to decrease heart rate while having little or no effect on blood pressure. The overall  blood pressure and heart rate changes produced by propranolol at 5 mg/kg differed significantly from those of the control group at both the 4 and 16-18 hr post-dosing intervals. Metoprolol at 5 mg/kg produced significant overall changes in blood pressure and heart rate only at the 4 hr post-doing interval. D-propranolol had no effect on either blood pressure or heart rate. The results indicate tha s.c. propranolol and metoprolol lower systolic blood pressure in conscious DOC-saline hypertensive rats only at the higher dose of 5 mg/kg and that cardioselectivity does not afford increased antihypertensive activity in this model.
D000818:Animals; D000959:Antihypertensive Agents; D001794:Blood Pressure / Q000187:drug effects; D003900:Desoxycorticosterone / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects; D006973:Hypertension / Q000139:chemically induced; D008297:Male; D008790:Metoprolol / Q000494:pharmacology*; D011412:Propanolamines / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D000959:Antihypertensive Agents; D011412:Propanolamines; D003900:Desoxycorticosterone; D011433:Propranolol; D008790:Metoprolol