EFFECTS OF BETA-ADRENOCEPTOR BLOCKING-AGENTS, PINDOLOL, ALPRENOLOL AND PRACTOLOL ON BLOOD-PRESSURE AND HEART-RATE IN CONSCIOUS RENAL HYPERTENSIVE DOGS

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  • 1 January 1977
    • journal article
    • research article
    • Vol. 225  (1) , 152-165
Abstract
The effects of oral pindolol (10 mg/kg), alprenolol (50 mg/kg) and practolol (50 mg/kg) on blood pressure and heart rate were investigated over a 24 h period in 5 conscious renal hypertensive dogs using a cross-over design. Pindolol and alprenolol caused significant falls in blood pressure which averaged 22 mm Hg (at 3 h after oral administration) and 20 mm Hg (at 3 h). Practolol failed to produce any significant changes in blood pressure. Heart rate increased by 67 beats/min (at 1 h) and 39 beats/min (at 3 h) after pindolol and alprenolol, respectively, but did not show any significant increase when practolol was given orally. The pindolol-induced tachycardia and hypotension were not suppressed significantly by propranolol (1 mg/kg i.v.) which blocked completely the tachycardia and hypotension induced by isoprenaline (3 mg/kg orally). The hypotension and tachycardia observed after oral administration of D-32 [d,l-1-tert-butylamino-3-(2'',3''-dimethylphenoxy)-2-propanol hydrochloride] (50 mg/kg) or after i.v. infusion of p-OH D-32 (1 mg/kg per min for 5 min) were also not modified significantly by propranolol (1 mg/kg i.v.). Based on these results and other published data, mechanisms pertaining to the hypotension exerted by .beta.-adrenoceptor blocking agents were discussed.