Ca2+ homeostasis and cytotoxicity in isolated hepatocytes: Studies with extracellular adenosine 5′-triphosphate

✍ Scribed by Mirabelli, Francesca ;Bellomo, Giorgio ;Nicotera, Pierluigi ;Moore, Margo ;Orrenius, Sten

• Book ID: 102874507
• Publisher: John Wiley and Sons
• Year: 1986
• Tongue: English
• Weight: 618 KB
• Volume: 1
• Category: Article
• ISSN: 0887-2082
• DOI: 10.1002/jbt.2570010105

✦ Synopsis

The incubation of isolated rat hepatocytes with extracellular adenosine 5'-tri hosphate (ATP) resulted in an inhibition of Ca2+ efflux. The ATP-induced C$+ accumulation as determined by the increase in phosphorylase a activity and the Ca2+-sensitive fluorescent indicator (2-[(2-bis-[carboxymethyl]-amino-5-methylphenoxy)-methyl]-6-methoxy-8-b~s-[carboxymethyll aminoquinoline-tetrakis-[acetoxymethyl]ester) (Quin 2-AM) was associated with both the hydrolysis of ATP and the phosphorylation of a 110 kDa protein. NO significant alteration in the intracellular ATP level was observed.

The appearance of surface blebs and cytotoxicity followed the rise in cytosolic Ca2+, suggesting that the increased free Ca2+ may be responsible for the loss of viability. When a calmodulin inhibitor, l-[bis(4-chlorophenyl)methyll-3-[2-(2,4-dichlorophenyl)-2-[(2,4-dichlorophenyl)methoxy] ethyl]-1H-imidazolium chloride (calmidazolium), was included in the medium prior to ATP addition, bleb formation was reduced and the loss of viability was completely prevented, indicating that a Ca2+-calmodulin process may be involved in the initiation of cytotoxicity.