Preservation of Glucose Transport and Enzyme Activity in Fish Intestinal Brush-border and Basolateral Membrane Vesicles

The preservation of glucose transport and membrane-bound enzyme activity in intestinal brush-border and basolateral membrane vesicles from the euryhaline teleost, Oreochromis mossambicus, was examined. Transport was well-preserved when the vesicles were either frozen in liquid nitrogen or lyophilized and stored in the presence of trehalose. Transport activity was not well-maintained when vesicles were lyophilized with mannitol as the protective carbohydrate. Enzyme activities were reduced by liquid nitrogen storage or by lyophilization with mannitol. However, enzyme enrichments of all treatments remained fairly constant over storage time, suggesting similar functional and perhaps structural changes in the different membrane fractions in response to preservation. These techniques provide a simple way to obtain functionally similar vesicles over a relatively long period of storage, permitting improved comparisons of transport properties. These results extend for the first time to vertebrate epithelial membranes the finding that trehalose preserves transport activity during lyophilization, storage and rehydration.