Tyrosine protein kinase inhibitors prevent activation of cardiac swelling-induced chloride current.
The effect of tyrosine protein kinase inhibitors on the swelling-induced chloride current (ICl-swelling) of dog atrial myocytes was studied using the whole-cell patch-clamp recording technique. Currents were measured during hyperpolarizing voltage ramps with potassium currents blocked by cesium. Osmolarity was varied using mannitol. Exposure to hypotonic solution (approximately 249 mosmol/kg) activated ICl-swelling. Hypertonic solution (approximately 363 mosmol/kg) was used to shrink swollen cells and turn off ICl-swelling. In studies on the acute effect of tyrosine protein kinase inhibitors each cell was swollen three separate times. Control, treatment, and washout ICl-swelling were compared. Genistein (50-80 microM) prevented reactivation of ICl-swelling without affecting cell size. The effect of genistein partially subsided upon washout. The effect of genistein on ICl-swelling was not mimicked by 80 microM daidzein, a related compound that does not inhibit tyrosine protein kinases. When intracellular adenosine 5'-O-(3-thiotriphosphate (ATP[gamma S]) was used, genistein did not prevent the reactivation of ICl-swelling. Intracellular ATP[gamma S] did not result in a persistent activation of ICl-swelling when cell size was returned to control. Acute exposure to 1 microM herbimycin A or 100 microM tyrphostin 51 did not prohibit the activation of ICl-swelling. A 24-h exposure to 1 microM herbimycin A did inhibit ICl-swelling. The results provide important clues regarding the activation mechanism for ICl-swelling and suggest that a tyrosine protein phosphorylation may be necessary, but not sufficient, for activation of ICl-swelling.
Sorota
S
S
Department of Pharmacology, Columbia University, New York, NY 10032, USA.
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D016227:Benzoquinones; D048429:Cell Size / Q000502:physiology; D018118:Chloride Channels / Q000187:drug effects / Q000378:metabolism*; D004285:Dogs; D004594:Electrophysiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019833:Genistein; D006321:Heart / Q000187:drug effects*; D007038:Hypotonic Solutions; D066298:In Vitro Techniques; D007529:Isoflavones / Q000494:pharmacology; D047029:Lactams, Macrocyclic; D008564:Membrane Potentials / Q000502:physiology; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D010766:Phosphorylation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D011809:Quinones / Q000494:pharmacology; D017828:Rifabutin / Q000031:analogs & derivatives
D016227:Benzoquinones; D018118:Chloride Channels; D004791:Enzyme Inhibitors; D007038:Hypotonic Solutions; D007529:Isoflavones; D047029:Lactams, Macrocyclic; D011809:Quinones; D017828:Rifabutin; C022571:adenosine 5'-O-(3-thiotriphosphate); C020754:herbimycin; D000255:Adenosine Triphosphate; D019833:Genistein; D011505:Protein-Tyrosine Kinases