Effects of glutaraldehyde fixative osmolarities on smooth muscle cell volume, and osmotic reactivity of the cells after fixation

The contribution of glutaraldehyde (GA) to the effective osmolarity of GA fixatives, the osmotic reactivity of the cells after fixation in GA, and also the duration of fixation in GA on cell volume, were investigated using cultured smooth muscle cells (SMC) and spiral aortic strips. Four fixation procedures were studied. We found that GA contributes to the total effective osmolarity of the fixatives, and that the type of buffers used for the fixatives can also affect the cell volume differently during GA fixation. After GA fixation, the cells were still osmotically reactive, regardless of the buffer types for making up the GA fixatives, so that the osmolarity of the wash buffer after GA fixation is important. However, OsO4 eliminates osmotic responses, thus the osmolarity of OsO4 fixative and wash buffer have negligible influence on the cell volume. Longer fixation time up to 4 h had no effect of the cell volume.