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Ion‐channel currents of smooth muscle cells isolated from the prostate of guinea‐pig
Author(s) -
Oh S.J.,
Kim K.M.,
Chung Y.S.,
Hong E.K.,
Shin S.Y.,
Kim S.J.
Publication year - 2003
Publication title -
bju international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.773
H-Index - 148
eISSN - 1464-410X
pISSN - 1464-4096
DOI - 10.1111/j.1464-410x.2003.04510.x
Subject(s) - tetraethylammonium , depolarization , chemistry , patch clamp , apamin , biophysics , cardiac transient outward potassium current , iberiotoxin , membrane potential , voltage clamp , ion channel , egta , charybdotoxin , guinea pig , repolarization , nifedipine , potassium channel , electrophysiology , endocrinology , medicine , potassium , calcium , biochemistry , biology , receptor , organic chemistry
OBJECTIVE To characterize the voltage‐activated ion‐channel currents in guinea‐pig prostate smooth muscle cells (GPSMCs). MATERIALS AND METHODS GPSMCs were isolated using collagenase, and used in a whole‐cell patch clamp study. RESULTS When GPSMCs were dialysed with a CsCl solution all the outward K + currents were blocked and the step‐like depolarization (holding voltage − 70 mV) of the cell membrane evoked inward currents that were completely blocked by nifedipine (1 µmol/L). With KCl solution, step depolarizations showed outward K + currents composed of fast, transient outward current (I to ) and outward currents that did not inactivate. I to was resistant to a high concentration of tetraethylammonium (TEA, 5 mmol/L) but was blocked by 4‐aminopyridine (5 mmol/L). The half‐activation and half‐inactivation voltages of I to were 6 mV and − 58 mV, respectively. With low Ca 2+ buffer (0.1 mmol/L EGTA) in the solution, there were spontaneous transient outward currents (STOCs) at depolarized membrane voltages (0 mV). STOCs were blocked by TEA (1 mmol/L) or iberiotoxin (10 nmol/L) but were insensitive to apamin (100 nmol/L). CONCLUSION This voltage‐clamp study showed that GPSMCs have l ‐type Ca 2+ channels and more than two types of K + channels. The voltage‐ and time‐dependent changes of these ion channels and their interactions might be important in forming action potentials and regulating contractility.