Effect of reversible ATP depletion on tight-junction integrity in LLC-PK1 cells.

To further understand and investigate how ischemia affects the tight junction we have developed a 2-h model of rapidly reversible ATP depletion and cellular injury in confluent LLC-PK1 monolayers. ATP depletion was achieved utilizing substrate-free medium containing 0.1 microM antimycin A (AA). Cellular ATP levels dropped rapidly to less than 5% of control values, but recovery of ATP and cell morphology was possible even after 2 h of exposure to AA. Ruthenium red, an electron-dense marker of tight-junction integrity, was excluded from the tight junctions of control monolayers but penetrated cellular tight junctions during ATP depletion in a duration-dependent manner. Electrical resistance across the monolayers remained unchanged in control monolayers but decreased linearly during ATP depletion to 59% of control values. Transmonolayer movement of [3H]mannitol increased from a control level of 7 to 13.5% during ATP depletion. Recovery of tight-junction integrity was demonstrated by a slowing of [3H]mannitol...