The role of a purinergic P2z receptor in calcium-dependent cell killing of isolated rat hepatocytes by extracellular adenosine triphosphate.
Extracellular adenosine triphosphate (ATP o) (0.4 mmol/L), a P2-purinergic receptor agonist, induces cytolysis in several cell types including isolated rat hepatocytes. In this study, we investigated the P2-receptor involved in ATP o-induced, Ca2+-dependent cytotoxicity in hepatocytes. Pretreatment of hepatocytes with oxidized ATP, a P2z-receptor antagonist, or complexation of ATP(4-) (the agonist for the P2z-receptor) with an excess of Mg2+, prevented ATP o-induced cell death. Both protective treatments also prevented the development of a sustained high intracellular Ca2+ concentration as well as the subsequent accumulation of inorganic phosphate (Pi). The P2Z-receptor agonist 3'-O-'(4-benzoylbenzoyl)-ATP (BzATP) was twofold more potent than ATP in eliciting cytolysis, which was preceded by a sustained high intracellular Ca2+ concentration; pretreatment with oxidized ATP prevented both the increase in the intracellular Ca2+ concentration and cell death. Prevention of ATP o-induced cell death, as well as the increases in the intracellular Ca2+ concentration and inorganic phosphate (Pi) was also achieved by decreasing the pH o to 6.9. Together the findings indicate that Ca2+-dependent cell killing by extracellular ATP in hepatocytes is mediated by a P2Z-receptor. The cytolytic effects correlated specifically with a secondary "late" increase in the intracellular Ca2+ concentration.
Zoetewij
J P
JP
Division of Toxicology, Leiden-Amsterdam Center for Drug Research, Leiden University, The Netherlands.
van de Water
B
B
de Bont
H J
HJ
Nagelkerke
J F
JF
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000502:physiology*; D016923:Cell Death / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008099:Liver / Q000166:cytology / Q000187:drug effects*; D008274:Magnesium / Q000494:pharmacology; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000502:physiology*
D018048:Receptors, Purinergic P2; D000255:Adenosine Triphosphate; D008274:Magnesium; D002118:Calcium