Modification of K+ conductance of heart cell membrane by BRL 34915.
1. The effect of the K+ channel agonist BRL 34915 on membrane conductance was investigated in isolated guinea-pig cardiac myocytes. 2. BRL 34915 reduced the duration of the transmembrane action potential and slightly increased the membrane resting potential in a concentration-dependent manner. 3. BRL 34915 removed the rectification in the steady-state current-voltage relationship. At membrane potentials more negative than the K+ equilibrium potential, membrane conductance was reduced. In the presence of 10(-4) mol/l BRL 34915, the current-voltage relationship was linear, i.e. of an ohmic type. 4. The BRL 34915-mediated change in membrane conductance was susceptible to the K+ channel blockers BaCl2 and tetrahydroaminoacridine. 5. In conclusion, BRL 34915 modifies K+ conductance in the cardiac cell membrane. The precise nature of the K+ conductance change remains to be elucidated.
Osterrieder
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Pharmaceutical Research Department, F. Hoffmann-La Roche & Co., Ltd., Basel, Switzerland.
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001578:Benzopyrans / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D019806:Cromakalim; D005260:Female; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D011758:Pyrroles / Q000494:pharmacology*
D000959:Antihypertensive Agents; D001578:Benzopyrans; D011758:Pyrroles; D019806:Cromakalim; D011188:Potassium