The effects of Bay K 8644 and nifedipine on the neural responses of the rabbit ear artery

• Published in: British journal of pharmacology 1986-06, Vol.88 (2), p.363-368
• Main Authors: Cheung, D.W., MacKay, M.J.
• Format: Article
• Language: English
• Subjects: 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; Animals; Applied sciences; arteries; Arteries - innervation; BAY K 8644; Biological and medical sciences; Cardiovascular system; Ear - blood supply; Exact sciences and technology; In Vitro Techniques; Medical sciences; membrane potential; Membrane Potentials - drug effects; Miscellaneous; Muscle Contraction - drug effects; Muscle, Smooth, Vascular - drug effects; nifedipine; Nifedipine - analogs & derivatives; Nifedipine - pharmacology; Other techniques and industries; Pharmacology. Drug treatments; Rabbits; smooth muscle
• ISSN: 0007-1188; 1476-5381
• DOI: 10.1111/j.1476-5381.1986.tb10212.x

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.