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Effects of neuropeptide Y on L‐type calcium current in guinea‐pig ventricular myocytes
Author(s) -
Bryant S.M.,
Hart G.
Publication year - 1996
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.1476-5381.1996.tb15560.x
Subject(s) - calcium , endocrinology , medicine , guinea pig , chemistry , neuropeptide y receptor , patch clamp , myocyte , voltage dependent calcium channel , voltage clamp , biophysics , calcium channel , calcium in biology , membrane potential , electrophysiology , biology , neuropeptide , biochemistry , receptor
1 Neuropeptide Y (NPY) reduces cell shortening at high concentrations in guinea‐pig ventricular myocytes. We have studied the effects of the peptide on calcium current in cardiac myocytes. 2 We have recorded L‐type calcium current in guinea‐pig ventricular myocytes under conditions in which the effects of other overlapping currents have been minimised by using Na + ‐free, K + ‐free external solution and patch‐clamp electrodes containing Cs + . 3 Peak inward calcium current is reduced by NPY at concentrations in excess of 1 nM, and maximal inhibition (31%) was found at and above concentrations of 100 nM. The IC 50 value for NPY inhibition of peak calcium current was 1.72 nM. 4 NPY had no effect on the voltage‐dependence of calcium current amplitude, on the time course of current inactivation, or on the voltage‐dependence of the steady‐state gating variables. 5 NPY did not reduce the calcium current in the presence of 8‐Br‐cyclic AMP, and it was also without effect when GTP‐γ‐S or GDP‐β‐S were included in the patch pipette. 6 We conclude that in guinea‐pig ventricular myocytes NPY acts at low concentration to reduce L‐type calcium current, via a G‐protein‐mediated pathway and reduction in intracellular cyclic AMP.