Cardiovascular responses to injections of cholinomimetic drugs into the cerebral ventricles of unanaesthetized dogs
Open Access
- 1 February 1973
- journal article
- Published by Wiley in British Journal of Pharmacology
- Vol. 47 (2), 196-205
- https://doi.org/10.1111/j.1476-5381.1973.tb08317.x
Abstract
1 The cardiovascular and behavioural effects of cholinomimetic drugs injected through a cannula chronically implanted into a lateral cerebral ventricle were examined in unanaesthetized dogs. 2 Acetylcholine (ACh) (10–20 μg) produced an increase in arterial pressure and heart rate, the dogs became more alert, moved their heads, licked and swallowed and then became drowsy. 3 The responses to ACh were potentiated by intraventricular physostigmine (5 μg), were abolished by intraventricular atropine (100 μg) but were unaffected by intraventricular mecamylamine (250 μg). The responses to ACh were reproducible on any one day if injections were given again after a 30 min interval but tolerance developed when ACh was injected repeatedly over periods of several days. 4 Methacholine (40 μg) produced similar behavioural and cardiovascular effects to ACh but of a longer duration. The responses to methacholine were abolished by intraventricular atropine (100 μg). 5 Nicotine (20–60 μg) produced a biphasic cardiovascular response of an initial brief pressor response and tachycardia followed by a secondary increase in arterial pressure and heart rate which was greater in magnitude and duration. The secondary cardiovascular effects were associated with restlessness and vomiting. 6 The responses to nicotine were abolished by prior injection of mecamylamine (250 μg) but were unaffected by atropine (100 μg). The responses to nicotine were not reproducible if injections were repeated on the same day but could be again produced if a few days were allowed to elapse between injections. 7 An increased heart rate occurred during the pressor response to the cholinomimetic drugs but when a comparable pressor response was produced by intravenous infusion of noradrenaline in the same unanaesthetized dogs pronounced reflex bradycardia resulted. 8 The results indicate that the activation of both muscarinic and nicotinic cholinergic mechanisms leads to cardiovascular and behavioural effects in the conscious dog although the site of action and peripheral mechanisms have not been determined.Keywords
This publication has 15 references indexed in Scilit:
- Analysis of the central vasomotor effects of cholineEuropean Journal of Pharmacology, 1969
- Effect of nembutal on arterial pressure responses evoked by stimulation of the hypothalamus, medulla, and lateral horns of the spinal cordBulletin of Experimental Biology and Medicine, 1968
- THE EFFECTS OF INTRAVENTRICULAR ADMINISTRATION OF NICOTINE ON BLOOD PRESSURE AND SOME SOMATIC REFLEXES*Annals of the New York Academy of Sciences, 1967
- EFFECTS OF NICOTINE ADMINISTRATION TO THE CAT'S LOWER BRAIN STEM UPON ELECTROENCEPHALOGRAM AND AUTONOMIC SYSTEM*Annals of the New York Academy of Sciences, 1967
- CHOLINERGIC TRANSMISSION IN THE MAMMALIAN CENTRAL NERVOUS SYSTEMPublished by Elsevier ,1965
- The identification of acetylcholine in presynaptic terminals isolated from brainBiochemical Pharmacology, 1963
- Some Antagonists of Atropine-Like PsychotomimeticsJournal of Pharmacy and Pharmacology, 1963
- PERFUSION OF CEREBRAL VENTRICLES: ASSAY OF PHARMACOLOGICALLY ACTIVE SUBSTANCES IN THE EFFLUENT FROM THE CISTERNA AND THE AQUEDUCTBritish Journal of Pharmacology and Chemotherapy, 1958
- Effect of Intracisternal Injections of AcetylcholineExperimental Biology and Medicine, 1935