The relationship between intracellular Ca2+ and the mitochondrial membrane potential in isolated proximal tubular cells from rat kidney exposed to the nephrotoxin 1,2-dichlorovinyl-cysteine.
The effects of 1,2-dichlorovinyl-cysteine (DCVC) on the intracellular free calcium concentration ([Ca2+]i) and the mitochondrial membrane potential (delta phi) were investigated in freshly isolated rat kidney proximal tubular cells (PTC). Prior to cell death, DCVC induced a rise in [Ca2+]i and a decrease in the delta phi. Omission of extracellular calcium still resulted in a DCVC-induced increase of [Ca2+]i, indicating that calcium was released from intracellular stores. The beta-lyase inhibitor amino-oxyacetic acid completely protected against mitochondrial damage and cell death, indicating that the DCVC effects are dependent on beta-lyase metabolism. Incubation of the PTC with DCVC together with the intracellular-calcium complexing agents EDTA/acetoxy-methyl (AM), EGTA/AM or Quin-2/AM delayed (but did not prevent) the decrease of the delta phi and cell death, which indicates a relationship between [Ca2+]i and the decrease of delta phi. In individual cells four different responses induced by DCVC were observed; an increase of [Ca2+]i without an effect on delta phi, a decrease of delta phi and an increase of [Ca2+]i occurring simultaneously; an increase of [Ca2+]i preceded by a decrease of delta phi and a decrease of delta phi without any increase of [Ca2+]i. This indicates that DCVC-induced effects on [Ca2+]i and delta phi can appear independently. The data show that mitochondrial damage is potentiated by an elevation of [Ca2+]i, thereby creating a situation which rapidly leads to cell death.
van de Water
B
B
Division of Toxicology, University of Leiden, The Netherlands.
Zoetewey
J P
JP
de Bont
H J
HJ
Mulder
G J
GJ
Nagelkerke
J F
JF
D000634:Aminoquinolines; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003545:Cysteine / Q000031:analogs & derivatives* / Q000633:toxicity; D004492:Edetic Acid; D004533:Egtazic Acid; D005434:Flow Cytometry; D007687:Kidney Tubules, Proximal / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D000634:Aminoquinolines; D004533:Egtazic Acid; C039961:S-(1,2-dichlorovinyl)cysteine; D004492:Edetic Acid; D003545:Cysteine; C035739:Quin2; D002118:Calcium