The Tegument of the Human Parasitic Worm Schistosoma mansoni as an Excretory Organ: The Surface Aquaporin SmAQP Is a Lactate Transporter
Figure 5
A–B. Increase in water osmotic permeability in oocytes expressing SmAQP. A. Volume increase in control, non- injected (NI) oocytes versus oocytes expressing SmAQP when transferred from normal salt solution (206 mOsm/Kg) to a hypotonic solution (72 mOsm/Kg) in the presence or absence of phloretin (0.5 mM). B. The osmotic permeability coefficient Pf of oocytes expressing SmAQP or control, non-injected (NI) oocytes in the presence (+) or absence (−) of phloretin (0.5 mM) (n = 3–6). C–D. Phloretin inhibition of water permeability and solute diffusion. C. The transport of lactate is inhibited by phloretin (0.5 mM, grey bars), but not by HgCl2 (0.3 mM, black bars). “+” signifies oocytes expressing SmAQP, “−” indicates control, non-injected oocytes. D. Kinetics of phloretin inhibition of lactate transport. Phloretin inhibits lactate movement with high affinity (Ki50 = 22 µM, n = 15–16). Values obtained from control oocytes, not-expressing SmAQP have been subtracted to generate the data shown. Data represent the mean ± SE generated in at least 2 independent experiments.