The mouse renal collecting duct is a heterogeneous segment of the nephron composed of principal cells and three types of intercalated cells Ca, p and non-a non-p intercalated cells). The selective expression of K+ and cr channels in the plasma membranes of these cells plays an important role in K+ and cr handling, maintaining the resting membrane potential and transport function and cell volume regulation in these cell types. The M8 collecting duct cell line is a new model of the collecting duct from embryonic day 18 mice. In the first section of the study we characterized the M8 cells by investing mRNA expression patterns. The mRNA expression favored a principal cell-like cell model, which lacked some key principal cell markers. Stimulating differentiation by increasing temperature had no effect, suggested a fully differentiated cell line. The whole-cell patch-clamp technique was used to investigate the physiological properties of anion and cation currents in the cells. A large cr conductance demonstrated properties similar to that of ICJ(swellh which is found in variety of tissues. Functionally ICI(swell) is involved in the regulation of cell volume. A smaller Ca2+-insensitive inwardly rectifying K+ conductance was assumed to help maintain the resting membrane potential. K+ channels in the cortical collecting duct have been studied for over 20 years and there is much molecular and functional evidence in the literature. A technique to measure the tubule diameter allowed us to measure the response of the cortical collecting duct to a hypotonic shock. Through the application of selective blockers a role was identified for Ca2+-activated K+ channels and Kir channels in volume regulation of the cortical collecting duct. In contrast, a much smaller body of evidence is available on the physiological role of cr channels in the cortical collecting duct. Whole-cell recordings from intercalated cells of the cortical collecting duct demonstrated a CIC-K2-Iike current, consistent wiII previous evidence suggesting CIC-K2 is involved in the cr recycling and reabsorption across the basolateral membrane.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:485073 |
| Date | January 2007 |
| Creators | Taylor, Helen Catherine |
| Publisher | University of Sheffield |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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