摘要:

SUMMARY1. The cardiovascular effects of acute and long‐term (4–7 weeks) treatment with propranolol and guanethidine were observed in conscious, DOCA/salt‐treated hypertensive rats.2. During long‐term treatment with a low dose of propranolol (0.2 mg/kg, subcutaneously, twice daily), the blood pressure is reduced to normotensive levels.3. The subcutaneous injection of 0.2 mg/kg of propranolol lowers blood pressure and heart rate for 2–4 h at the start of long‐term treatment, but these acute effects become less as treatment continues.4. Long‐term treatment with a high dose of propranolol (5 mg/kg, subcutaneously, twice daily) reduces heart rate but not blood pressure.5. The acute effects of subcutaneous injection of 5 mg/kg of propranolol are a rise in blood pressure and a fall in heart rate; these effects are maintained throughout the period of long‐term treatment.6. Guanethidine (5 mg/kg, subcutaneously, once daily) produces a gradual fall in blood pressure. The acute depressor effect becomes less as treatment continues.7. Observations were made on the responses to noradrenaline injections and thoraco‐lumbar stimulation in pithed rats, pretreated 1 h beforehand with propranolol (0.2 or 5 mg/kg) or guanethidine (5 mg/kg).8. Pressor responses to noradrenaline are slightly increased by all three pretreatments; the tachycardia produced by noradrenaline is increased by guanethidine and reduced by propranolol.9. The pressor response to thoraco‐lumbar stimulation is abolished by guanethidine and not affected by either dose of propranolol; the tachycardia is reduced by guanethidine and the high dose of propranolol (5 mg/kg) but not by the low dose.10. The antihypertensive action of propranolol in DOCA/salt‐treated rats can not be attributed to adrenergic neurone blockade or to a non‐specific depressant effect, and does not appear to be due to a dose‐dependent antagonistic effect on cardiac β‐receptors. It is suggested that it is due to a central impair

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1974.tb00530.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY