Enhancement of Intracellular Cl^- Concentrations Induced by Extracellular ATP in Guinea Pig Ventricular Muscle

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Abstract

We investigated effects of extracellular ATP on intracellular chloride activities ([Cl<SUP>-</SUP>]<SUB>i</SUB>) and possible contribution of the Cl<SUP>-</SUP>-HCO<SUB>3</SUB><SUP>-</SUP> exchange to this increase in [Cl<SUP>-</SUP>]<SUB>i</SUB> in isolated guinea pig ventricular muscles. The [Cl<SUP>-</SUP>]<SUB>i</SUB> and intracellular pH (pH<SUB>i</SUB>) were recorded in quiescent ventricular muscles using double-barreled ion-selective microelectrode techniques. MgATP at a concentration higher than 0.1mM, induced an increase in [Cl<SUP>-</SUP>]<SUB>i</SUB>, and this increase in [Cl<SUP>-</SUP>]<SUB>i</SUB> was dependent on the concentration of ATP but not on the concentration of magnesium ions present in the perfusion solution. NaADP, but not NaAMP, at a concentration of 0.5mM induced a similar increase in [Cl<SUP>-</SUP>]<SUB>i</SUB> as that induced by MgATP. However, the NaADP-induced increase in [Cl<SUP>-</SUP>]<SUB>i</SUB> was transient and gradually returned to the control level even though NaADP was continuously present. Furthermore, ATP also triggered a transient acidification of pH<SUB>i</SUB>, and both increases in [Cl<SUP>-</SUP>]<SUB>i</SUB> and intracellular H<SUP>+</SUP> induced by ATP were prevented when preparations were pretreated with stilbene derivatives, SITS and DIDS, or perfused with a Cl<SUP>-</SUP>-free solution. Our findings showed that the increased extracellular ATP concentrations might trigger an increase in [Cl<SUP>-</SUP>]<SUB>i</SUB> in ventricular muscles. In light of previous studies showing that cardiac ischemia induced increases in extracellular nucleotide concentrations and [Cl<SUP>-</SUP>]<SUB>i</SUB> in ventricular muscles, we propose that ischemia-induced accumulation of ATP concentration in the extracellular space may be an important factor to trigger increment of [Cl<SUP>-</SUP>]<SUB>i</SUB> during ischemic conditions.

Journal

  • The Japanese Journal of Pharmacology

    The Japanese Journal of Pharmacology 84(4), 438-448, 2000-12-01

    The Japanese Pharmacological Society

References:  49

Cited by:  1

Codes

  • NII Article ID (NAID)
    10008186787
  • NII NACSIS-CAT ID (NCID)
    AA00691188
  • Text Lang
    ENG
  • Article Type
    Journal Article
  • ISSN
    00215198
  • NDL Article ID
    5612105
  • NDL Source Classification
    ZS51(科学技術--薬学)
  • NDL Call No.
    Z53-D199
  • Data Source
    CJP  CJPref  NDL  J-STAGE 
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