title: Properties of a protein kinase C-activated chloride current in guinea pig ventricular myocytes.
abstract: Cardiac ventricular myocytes from several species, including the guinea pig, possess a cAMP-dependent protein kinase A (PKA)-activated Cl- channel. In the present study, the properties of a protein kinase C (PKC)-activated Cl- current were studied in isolated guinea pig ventricular myocytes using the whole-cell arrangement of the patch-clamp technique. Intracellular dialysis of ventricular cells with PKC resulted in the activation of a large background current that displayed time-independent kinetics. In the presence of 146 mmol/L external Cl- and 71 mmol/L internal Cl-, the reversal potential (Erev) of the background current (-17 +/- 1 mV) was close to that of the Cl- equilibrium potential (-18 mV), and the current versus voltage relation for the current was outward rectifying in shape. When [Cl-]i or [Cl-]o was reduced by substitution of Cl- with aspartic acid, Erev for the background current shifted in a manner expected for a Cl(-)-selective channel. Based on Erev measurements, the permeability sequence for this PKC-activated Cl- channel was determined to be SCN- > I- > Br- congruent to Cl-. The PKC-activated Cl- current was not inhibited by the Cl- channel blocker 4,4'-dinitrostilbene-2,2'-disulfonic acid (100 mumol/L) but could be blocked by anthracene-9-carboxylic acid (1 mmol/L). Activation of the current was abolished in the presence of the PKC inhibitor staurosporine (2.5 mumol/L). Under conditions designed to cause a maximal activation of the Cl- channels by PKC, the addition of forskolin (1 mumol/L) to stimulate PKA caused only a slight further increase in the amplitude of the Cl- current. Thus, PKC activates a Cl- channel in guinea pig ventricular cells with properties similar but not identical to the PKA-activated channel.
authors.affiliation: Department of Pharmacology, University of South Carolina, School of Medicine, Columbia 29208.
authors.forename: K B
authors.initials: KB
authors.lastname: Walsh
authors.forename: K J
authors.initials: KJ
authors.lastname: Long
mesh_terms: D000818:Animals; D000838:Anions / Q000378:metabolism; D018118:Chloride Channels / Q000378:metabolism / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology; D004594:Electrophysiology; D006168:Guinea Pigs; D006352:Heart Ventricles; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D010539:Permeability; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011493:Protein Kinase C / Q000502:physiology*
chemical_list: D000838:Anions; D018118:Chloride Channels; D015240:Phorbol 12,13-Dibutyrate; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C