Slow calcium and potassium currents across frog muscle membrane: measurements with a vaseline-gap technique.
J Physiol
; 312: 159-76, 1981 Mar.
Article
in En
| MEDLINE
| ID: mdl-6267261
ABSTRACT
1. A vaseline-gap voltage-clamp technique was used to record slow Ca2+ and K+ currents from frog skeletal muscle fibres loaded with the Ca2+ chelator EGTA. 2. K+ currents were increased when Mg2+ replaced external Ca2+, and they were abolished when internal K+ was replaced by tetraethylammonium (TEA+). Ca2+ currents could be studied in isolation in fibres loaded with (TEA)2EGTA. 3. Under maintained depolarization, Ca2+ currents slowly increase (half-time of 35 msec or more at 25 mV) and then decline to a steady value. Decline under repolarization is rapid (half-time of 6-7 msec) and complete. During an action potential, the Ca2+ influx through this system is probably less than the influx observed with tracers. 4. Ba2+, Sr2+, Ca2+, Mn2+ and Mg2+ can carry current across the membrane; Ni2+ and Co2+ cannot. Ca2+ currents are weakly blocked by external Mg2+.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Potassium
/
Calcium
/
Muscles
Limits:
Animals
Language:
En
Journal:
J Physiol
Year:
1981
Document type:
Article