Functional and ultrastructural cell pathology induced by fuel oil in cultured dolphin renal cells

Investigations were undertaken to elucidate in a marine mammal renal cell culture system the toxicity and some of the mechanisms of cytopathology in a standardized preparation following exposure to No. 1 fuel oil. Cell survivability of a cultured SP1K renal cell line from the Atlantic spotted dolphin Stenella plagiodon was reduced in a dose-dependent manner after a 12-h exposure to fuel oil. Early morphologic changes reflecting cytotoxicity, as revealed by transmission electron microscopy, included enlarged rough endoplasmic reticula, cytoplasmic vacuolization, and degenerative cytoplasmic inclusions, but mitochondria remained resistant. Assessment of extracellular proton loss by microphysiometry of cultured cells revealed fuel oil-induced enhancement of proton loss that was dependent upon both protein kinase C and renal epithelial Na(+)/H(+) counter-transport functioning, as the specific inhibitors H-7 and amiloride reduced this stimulatory petroleum effect. Cell cycle progression and apoptosis (programmed cell death) were studied in dolphin renal cells exposed to fuel oil for 12, 24, and 48 hours. The toxicant increased the percentage of cells in GO/GI phase and decreased the percentage of cells in S phase starting after 24 hours. The number of cells undergoing early apoptosis was also increased after 24 hours.