Rapid morphological reorganization of the rabbit corneal endothelium after acute exposure to sodium lactate in vitro.

Corneal stroma-endothelial preparations from 2-kg albino rabbits were incubated in vitro in a bicarbonate-Ringer solution equilibrated with 5% CO2-9% O2 over 4 h in half-chambers at 37 degrees C. An average net fluid pump activity of 6.8 microliters/h was measured in the 4th hour. If such preparations were initially equilibrated with bicarbonate-Ringer for 90 min and then challenged for 20 min with 15 mM sodium lactate or NaCl, an osmotically induced increase in fluid flow occurred. After removal of the challenge and return to bicarbonate-Ringer for 2.5 h, the net fluid pump returned to baseline and then increased again (to an average of 9.7 microliters/h) for the lactate- but not NaCl-challenged endothelia. Scanning electron microscopy showed that lactate-challenged (but not the control or NaCl-challenged) endothelial contained a moderate number of very large pleomorphic cells within an otherwise regular mosaic. It is proposed that the large cells develop as a result of cell fusion (coalescence).