Assessing the metabolic cost of ion transport using SIET and SPET

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A fundamental question in biology that has yet to be answered concerns the cost of moving ions across a cell. Epithelial ion transport is of critical importance to processes as diverse as cerebrospinal fluid formation, nutrient absorption, and regulation of salt/water balance, and our understanding of the ion transport mechanisms underlying epithelial ion transport is increasingly detailed and complex. However, although the cost of epithelial ion transport is thought to be significant, reliable experimental estimates of this cost have not yet been obtained, in large part owing to the technical challenges of simultaneously measuring ion movements and ATP use (or proxies thereof, such as O2 consumption) under physiologically-relevant conditions. The proposed research requires an assemblage of state-of-the-art instrumentation that currently is not available at the University of Ottawa, or anywhere in Canada for that matter: A system that combines use of the scanning ion electrode technique (SIET) with the scanning polarographic electrode technique (SPET). The current request is for the funding to purchase this instrumentation which is critical to the success of our proposed research and also to the training of HQP involved in the proposed research. Indeed, the opportunity to use this instrumentation will provide a training opportunity that is unique in Canada if not worldwide. We propose an innovative combination of SIET and SPET to quantify the metabolic costs of ion transport in fish ionocytes, chromaffin cells, enterocytes and kidney tubules. Ion fluxes will be measured by SIET while at the same time O2 fluxes will be measured by SPET