Premium
Sodium current kinetics in intact rat papillary muscle: measurements with the loose‐patch‐clamp technique.
Author(s) -
Antoni H,
Böcker D,
Eickhorn R
Publication year - 1988
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.1988.sp017376
Subject(s) - clamp , patch clamp , kinetics , biophysics , sodium , current (fluid) , chemistry , anatomy , sodium channel , biomedical engineering , electrophysiology , medicine , biology , physics , computer science , thermodynamics , clamping , organic chemistry , quantum mechanics , computer vision
1. Rapid inward sodium current (INa) was studied on intact rat papillary muscles and trabeculae excised from right or left ventricle using the loose‐patch‐clamp technique. All experiments were carried out at 25 degrees C. 2. Currents were recorded from patches with a large current density of mean 5.9 +/‐ 0.5 mA/cm2. 3. The current was reduced by tetrodotoxin (TTX) in a dose‐dependent manner. The concentration of TTX producing half‐maximal blockade of INa was 6.3 +/‐ 0.8 mumol/l. 4. Na+ current appeared upon depolarization at a threshold potential of about ‐55 mV and reached its maximum at about ‐20 mV. 5. Kinetic data were evaluated using the Hodgkin‐Huxley model. 6. Time constants of activation (tau m) were estimated using single‐pulse and tail‐current measurements. They had a maximum of about 0.4 ms near the threshold potential and declined at more positive and at more negative potentials to values near 0.1 ms. 7. Two time constants were necessary to describe inactivation. Both time constants had their maximal values of 135 +/‐ 8.1 and 29.1 +/‐ 5.9 ms at about ‐80 mV and decreased towards 4 and 0.5 ms at potentials positive to ‐20 mV.