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AN ANALYSIS OF THE RESPIRATORY STIMULANT EFFECT OF PHYSOSTIGMINE AND NEOSTIGMINE DM THE CONSCIOUS RABBIT
Author(s) -
Weinstock M.,
Roll D.,
Zilberman Y.
Publication year - 1981
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1981.tb00146.x
Subject(s) - physostigmine , neostigmine , atropine , chemistry , muscarinic acetylcholine receptor , hexamethonium , fasciculation , acetylcholine , anesthesia , respiratory system , cholinesterase , respiration , stimulant , endocrinology , medicine , receptor , biochemistry , anatomy
SUMMARY 1. The effects of physostigmine and neostigmine, given by continuous intravenous infusion, were studied on respiration in conscious rabbits. 2. Physostigmine (5 μg/kg per min) significantly increased respiration rate, decreased arterial PaCO 2 from 25.4 ± 0.9 to 19.8 ± 1.5 mmHg, increased PaCO 2 from 100.3 ± 1.9 to 108 ± 3.0 and pH from 7.42 ± 0.01 to 7.46 ± 0.01 within 30 min of its infusion. 3. Neostigmine (2.5 μg/kg per min) also decreased PaCO 2 and increased PaO 2 significantly, but caused a concomitant lactic acidosis, which was associated with the increased muscular activity and fasciculations. 4. The respiratory stimulant effect of neostigmine, but not that of physostigmine, was abolished by hexamethonium 2 × (1.5 mg/kg). Atropine methyl nitrate (1 mg/kg) failed to influence the respiratory stimulant effect of physostigmine, but hyoscine (10 mg/kg) blocked it completely. 5. It is suggested that augmentation of respiratory activity by neostigmine is mediated via peripheral nicotinic receptors in the carotid and aortic bodies. This may occur either through the accumulation of acetylcholine or of H + ions from raised blood lactic acid. 6. It is further suggested that physostigmine stimulates respiration by raising the concentration of acetylcholine in the central nervous system which, in turn, activates muscarinic receptors.