Effect of hypotonic shock on cell volume and intracellular calcium of trout gill cells.

Gill epithelium being a very complex structure, it was impossible to study the effect of an hypotonic shock on gill cells in situ. For this reason, a primary culture of trout gill cells was developed and the effect of the dil ution of extracellular medium was measured on these gill cultured cells. Gill cells in primary culture form a confluent monolayer of contiguous cell s after 5 to 7 days of culture. These cultured cells display ultrastructura l features resembling those of in situ respiratory cells. Measurements of cell volume, during a hypotonic shock, were made on isolate d cultured respiratory cells with a Coulter counter technique. A hypotonic shock (2/3rd Ringer) produces a cell swelling of 130% in 5 minutes. Then, c ells regulate their volume : after 30 minutes in hypotonic conditions, cell swelling represents 110% only of the initial value. By measuring intracellular calcium with a fluorescent probe sensitive to ca lcium (Fura-2), we observed that a hypotonic shock produces an intracellula r calcium increase in gill cultured cells.