MADIN-DARBY CANINE KIDNEY-CELLS ARE INJURED BY EXPOSURE TO OXALATE AND TO CALCIUM-OXALATE CRYSTALS

The reaction of Madin-Darby canine kidney cells (MDCK) to potassium ox alate (KOx), calcium oxalate monohydrate (COM) crystals, or a combinat ion of the two was studied. The most noticeable effect of exposure of the cells to either KOx or COM crystals was loss of cells from the mon olayer ranging from 20% to 30%, depending upon the particular treatmen t. Cellular enzyme values in the media were elevated significantly by 12 h of exposure, although in specific instances, elevated levels occu rred at earlier time periods. As regards the monolayer, trypan blue ex clusion was decreased significantly, although amounting to only a 4-5% reduction. Specific tritiated release occurred at 4 and 12 h after ex posure to KOx and at 12 h after exposure to crystals. Structurally, CO M-cell interactions were complex and extensive endocytosis was noted. Cells were released from culture either as cell-crystal complexes or f rom the intercellular spaces after exocytosis. When treatments were co mbined the effects were only slightly additive, but the two treatments potentiated each other: all media enzyme levels (with one exception) were elevated at 2 h, tritiated adenine release was present at 4 h, an d there was more extensive cell loss from the culture monolayer. These data suggest that both KOx and COM crystals damage MDCK cells when ap plied alone, and in concert they act synergistically.