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THE EFFECTS OF PHYSOSTIGMINE ON THE MECHANICAL AND ELECTRICAL RESPONSES OF THE CAT NICTITATING MEMBRANE
Author(s) -
BOWMAN W. C.,
CALLINGHAM B. A.,
CUTHBERT A. W.
Publication year - 1964
Publication title -
british journal of pharmacology and chemotherapy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0366-0826
DOI - 10.1111/j.1476-5381.1964.tb01710.x
Subject(s) - physostigmine , nictitating membrane , chloralose , cats , anesthesia , contraction (grammar) , chemistry , muscle contraction , medicine , acetylcholine , classical conditioning , mathematics , conditioning , statistics
The effects of physostigmine on the electrical and mechanical responses of the nictitating membrane elicited by single nerve shocks have been studied in cats anaesthetized with a mixture of chloralose and pentobarbitone. The results were variable but the most consistent effect, observed with large doses of physostigmine, was a depression and prolongation of the contractions which was sometimes associated with augmentation of the characteristic rhythmic electrical activity of the smooth muscle. Although the amplitude of single responses was depressed, incomplete tetanic contractions were sometimes increased in tension because of the greater fusion which occurred as a result of prolongation of the units of contraction. Possible mechanisms underlying the effect of physostigmine are discussed.