Premium
Kinetic evidence distinguishing volume‐sensitive chloride current from other types in guinea‐pig ventricular myocytes.
Author(s) -
Shuba L M,
Ogura T,
McDonald T F
Publication year - 1996
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.1996.sp021197
Subject(s) - forskolin , chemistry , myocyte , repolarization , biophysics , guinea pig , medicine , reversal potential , membrane potential , conductance , patch clamp , protein kinase c , endocrinology , electrophysiology , kinase , biology , biochemistry , physics , in vitro , condensed matter physics
1. Kinase‐mediated chloride currents (ICl) in guinea‐pig ventricular myocytes were activated by application of phorbol ester or forskolin, and compared with currents induced by hyposmotic swelling. Swelling‐activated current was identified as ICl from changes in reversal potential, outward rectification and conductance when the Cl‐gradient was modified. 2. Kinase‐stimulated currents were relatively time and voltage independent, whereas hyposmotic swelling‐stimulated (hyposmotic‐stimulated) currents inactivated during 100 ms pulses to positive potentials. Forskolin stimulated time‐independent ICl in myocytes with current unresponsive to hyposmotic superfusion, and superimposed a similar pedestal on time‐dependent ICl in swollen myocytes. 3. Less negative holding potentials depressed hyposmotic‐stimulated ICl tested at +80 mV; inhibition was half‐maximal at ‐25 mV. Pulses from ‐80 to +80 mV inactivated up to 75% of ICl along a multi‐exponential time course; repolarization elicited inwardly developing tail currents whose time courses suggest complex gating. 4. Hyperpolarizations, after strongly‐inactivating depolarizations, triggered reactivating tail currents whose amplitude and configuration were dependent on voltage and Cl‐gradients; tails were large and inwardly developing at potentials negative to the calculated Cl‐equilibrium potential (ECl), small and outwardly developing at potentials positive to ECl, and time independent near ECl. 5. These results suggest that the volume‐sensitive Cl‐ channels investigated here are distinct from other Cl‐ channels in guinea‐pig ventricular myocytes. However, their voltage‐dependent properties strongly resemble those of volume‐sensitive Cl‐ channels in certain epithelial cells.