Activation of chloride current by purinergic stimulation in guinea pig heart cells.
Single atrial cells from guinea pig heart were voltage-clamped using the whole-cell configuration of the patch-clamp technique under conditions in which most of the ionic and exchange currents known in cardiac cells were minimized. Extracellular 5 or 50 microM ATP activated a Cl- current, in addition to a rapidly desensitizing cation-selective current. A nonhydrolyzable ATP analogue, adenosine-5'-O-(3-thiotriphosphate) (50 microM), also evoked these two currents, indicating involvement of purinoceptors rather than ecto-ATPase on the membrane. ADP, AMP, and adenosine were also effective in inducing the Cl- current, showing no clear order of potency for the purinoceptor subtypes involved. The purinoceptor-activated Cl- current, like the beta-catecholamine-cAMP-dependent cardiac Cl- current, showed outward rectification and time independence.
Department of Physiology, Saga Medical School, Japan.
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Matsuura
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Ehara
D000227:Adenine Nucleotides / Q000494:pharmacology; D000241:Adenosine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D018118:Chloride Channels; D002712:Chlorides / Q000502:physiology*; D003584:Cytological Techniques; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects* / Q000502:physiology; D008565:Membrane Proteins / Q000187:drug effects* / Q000502:physiology; D009206:Myocardium / Q000166:cytology*; D011983:Receptors, Purinergic / Q000187:drug effects*; D013268:Stimulation, Chemical
D000227:Adenine Nucleotides; D018118:Chloride Channels; D002712:Chlorides; D007473:Ion Channels; D008565:Membrane Proteins; D011983:Receptors, Purinergic; D000255:Adenosine Triphosphate; D000241:Adenosine