Perturbations of intracellular calcium distribution in kidney cells by nephrotoxic haloalkenyl cysteine S-conjugates.

The Ca2(+)-sensitive dye fura-2 was used to investigate the disturbances in intracellular Ca2+ concentration [( Ca2+]i) and distribution induced by the nephrotoxic cysteine S-conjugate S-(1,2-dichlorovinyl)-L-cysteine (DCVC) and its homocysteine analog S-(1,2-dichlorovinyl)-L-homocysteine (DCVHC) in LLC-PK1 cells. After 24-hr treatment with DCVC, the average [Ca2+]i increased from 88 +/- 23 nM to 415 +/- 92 nM. Digital image analysis revealed that the mitochondrial region, which was stained with rhodamine-123, contained lower Ca2+ concentration ([Ca2+]) than other cell areas. This distribution was different from the higher [Ca2+] in the nuclear and mitochondrial regions observed in control cells. In DCVHC-treated cells, there was also an increase in [Ca2+]i to 355 +/- 85 nM, but the increase in [Ca2+] was greater in the mitochondrial region, compared with the rest of the cell. After 72-hr treatment with DCVC or DCVHC, the average [Ca2+]i was 410 +/- 85 nM and 340 +/- 90 nM, respectively, and blebs with markedly higher [Ca2+] (600-1000 nM) than the rest of the cell appeared in both DCVC- and DCVHC-treated cells. Moreover, in DCVC-treated cells the mitochondria could not be stained with rhodamine-123, indicating severe mitochondrial damage and loss of membrane potential. All changes described above took place in viable (propidium iodide-negative) cells. The experiments demonstrate that severe perturbations of intracellular Ca2+ distribution, particularly in the mitochondrial region, precede bleb formation and cell death in the course of development of toxicity by DCVC and DCVHC.