Investigation into the cardioregulatory properties of the alpha 1-adrenoceptor blocker indoramin

British Journal of Pharmacology
V PierceJ F Waterfall

Abstract

The cardioregulatory properties of the alpha 1-adrenoceptor blocker indoramin have been compared with those of prazosin in the anaesthetized rat. The effects of autonomic blockade on heart rate responses evoked by these two agents and their effects on blood pressure and heart rate after peripheral or central administration have been compared. Cumulative administration of indoramin (0.8-25.6 mg kg-1 i.v.) evoked significant decreases in arterial blood pressure and a concomitant bradycardia. Pithing or autonomic blockade, by pretreatment with a combination of practolol and bilateral vagotomy, prevented the bradycardia evoked by indoramin (0.8-3.2 mg kg-1 i.v.). Atropine sulphate pretreatment abolished the bradycardia until a cumulative dose of 25.6 mg kg-1(i.v.) of indoramin had been reached. Bilateral vagotomy, intravenous administration of atropine methylnitrate or practolol pretreatment attenuated the bradycardia. Prazosin (0.02-0.64 mg kg-1 i.v.) evoked a fall in arterial blood pressure of similar magnitude to that observed following indoramin. A bradycardia was evoked only at a relatively high dose (0.64 mg kg-1 i.v.). Intracisternal injection of indoramin or prazosin evoked bradycardia and hypotension at a dose which had no...Continue Reading

References

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Related Concepts

Metazoa
Diastolic Blood Pressure
Pulse Rate
Indoles
Wy-21901
Intravenous Injections
Injections, Intraventricular
Pratsiol
August Rats
Sympathetic Nervous System

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