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Influence of pH on the inhibitory action of local anaesthetics on smooth muscle contraction
Author(s) -
ANTONIO A.,
SILVA M.,
YASHUDA Y.
Publication year - 1970
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1970.tb10631.x
Subject(s) - inhibitory postsynaptic potential , chemistry , calcium , contraction (grammar) , depolarization , ethanol , muscle contraction , biophysics , smooth muscle , ileum , mechanism of action , membrane potential , pharmacology , biochemistry , endocrinology , biology , in vitro , organic chemistry
1 . The guinea‐pig isolated ileum kept in a calcium‐free depolarizing solution contracts when calcium is added; the responses are proportional to the concentration of calcium and are reversed by washing. 2 . The contractions elicited by calcium are inhibited by three different classes of compounds: local anaesthetics, pentobarbitone and ethanol. The inhibitory action of the local anaesthetics increases with an increase in pH, the inhibitory action of pentobarbitone increases with a decrease in pH and the inhibitory action of ethanol is not affected by variations in Tyrode pH. 3 . It is suggested that the antagonists are active when unionized and that the inhibition is obtained when unionized compounds have dissolved in the lipid material of the cell membrane. The possible site of action of the antagonists is discussed.