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Effects of activin A on ionic channels in human FSH‐secreting tumour cells.
Author(s) -
Takano K,
Ogata E,
Yamashita N
Publication year - 1994
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.1994.sp020003
Subject(s) - patch clamp , biophysics , depolarization , electrophysiology , membrane potential , chemistry , ion channel , voltage clamp , extracellular , reversal potential , conductance , current clamp , endocrinology , medicine , biology , biochemistry , physics , receptor , condensed matter physics
1. Effects of activin A on ionic channels were examined in human FSH‐secreting tumour cells using electrophysiological techniques. 2. Under voltage clamp with the conventional whole‐cell clamp technique, the voltage‐gated Na+ channel, the T‐ and L‐type Ca2+ channels, the delayed K+ channel and the A‐channel were observed. 3. With the nystatin‐perforated whole‐cell clamp technique, the same voltage‐gated channels were recorded. Activin A (10(‐7) M) increased the amplitude of the L‐type Ca2+ current, whereas it decreased the amplitude of the delayed K+ current. 4. Under current clamp with the perforated whole‐cell clamp technique, more than 80% of the cells exhibited spontaneous action potentials. Application of 10(‐7) M activin A depolarized the membrane with a conductance increase and augmented action potential frequency. The reversal potential of the activin A‐induced current was ‐20 to 0 mV. The activin A‐induced current was abolished in a Na(+)‐free extracellular solution, indicating that the membrane depolarization caused by activin A was due to the conductance increase to Na+ ions through non‐selective cation channels.