In vitro methods of assessing renal damage.

Freshly isolated and primary cultures of rat kidney cells derived from specific nephron segments can be useful in vitro models for studying processes such as drug metabolism, membrane transport, and biochemical mechanisms of chemically induced toxicity. Proximal tubular (PT) and distal tubular (DT) cells were isolated from rat renal cortex by collagenase perfusion and Percoll density-gradient centrifugation. Oxidants produced glutathione (GSH) oxidation and lipid peroxidation and were markedly more cytotoxic to DT cells than to PT cells. Similarly, alkylating agents that target soft nucleophiles such as GSH and protein sulfhydryls were more toxic to DT cells than to PT cells, whereas an alkylating agent that targets hard nucleophiles was equally cytotoxic in the 2 cell types. DT cells were also more sensitive to brief periods of oxygen deprivation and were markedly more susceptible to ATP depletion by treatment with iodoacetate and cyanide than were PT cells. Serum-free, hormonally defined conditions have been optimized for primary culture of rat renal PT and DT cells to maintain differentiated function for up to 9 days. Primary cultures exhibited similar susceptibilities as freshly isolated cells to acute injury from chemical toxicants and the cultures express several isoforms of cytochrome P-450. These studies show that freshly isolated and primary cultures of rat renal PT and DT cells can be used to study both short-term and long-term responses to toxic chemicals.