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The effects of Bay K 8644 and nifedipine on the neural responses of the rabbit ear artery
Author(s) -
Cheung D.W.,
MacKay M.J.
Publication year - 1986
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.1476-5381.1986.tb10212.x
Subject(s) - nifedipine , excitatory postsynaptic potential , contraction (grammar) , depolarization , inhibitory postsynaptic potential , stimulation , muscle contraction , membrane potential , bay , medicine , chemistry , anatomy , biophysics , endocrinology , calcium , biology , civil engineering , engineering
1 The effects of Bay K 8644 and nifedipine on the electrical and mechanical responses of the distal ear artery of the rabbit to stimulation of the perivascular nerves were studied. 2 Neural stimulation elicited excitatory junction potentials (e.j.ps) in the smooth muscle cells of the artery. An action potential was generated when the e.j.p. reached a threshold of about − 53 mV. Contraction was always triggered by the action potential. 3 Bay K 8644 at low concentrations (7 × 10 −8 M) had no significant effect on the resting membrane potential and the e.j.p. However the amplitudes of the action potential, and the contraction were potentiated by Bay K 8644. Multiple action potentials could also be generated from a single e.j.p. 4 At higher concentrations, Bay K 8644 (3 × 10 −6 M) caused membrane depolarization, development of vascular tone and spontaneous action potentials. All the effects of Bay K 8644 could be reversed by exposure to light. 5 Nifedipine (3 × 10 −7 M) inhibited the action potential and the resulting contraction. The effect of nifedipine could be reversed by Bay K 8644 but not by light. 6 These results demonstrate that the excitatory and inhibitory effects of Bay K 8644 and nifedipine on vascular smooth muscle are associated with changes in the electrical responses.