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Calcium‐dependent after‐potentials in visceral afferent neurones of the rabbit.
Author(s) -
Higashi H,
Morita K,
North R A
Publication year - 1984
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1984.sp015433
Subject(s) - hyperpolarization (physics) , egta , calcium , biophysics , chemistry , extracellular , potassium , intracellular , membrane potential , calcium in biology , conductance , electrophysiology , medicine , endocrinology , biochemistry , biology , stereochemistry , nuclear magnetic resonance spectroscopy , mathematics , organic chemistry , combinatorics
Intracellular recordings were made from neurones in nodose ganglia excised from rabbits. In C neurones, 1‐60 action potentials were followed by an after‐hyperpolarization with a peak amplitude of 16 mV and a time constant of decay ranging from 3 to 10 s. In A neurones, the action potentials were followed only by a brief (up to 50 ms) after‐hyperpolarization. The after‐hyperpolarization was associated with an increase in the membrane conductance to potassium ions; it reversed polarity at the potassium equilibrium potential. The increase in conductance following the action potentials was blocked by removal of calcium ions, or addition of cobalt to the extracellular solution. Intracellular injection of ethyleneglycol‐bis(beta‐aminoethylether)‐N,N'‐tetraacetic acid (EGTA) abolished the after‐hyperpolarization; intracellular injection of calcium mimicked the after‐hyperpolarization. It is concluded that calcium entry during the action potential leads to a long‐lasting increase in potassium conductance in visceral afferent C neurones.