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Evidence for facilitated diffusion of urea across the gill basolateral membrane of the rainbow trout (Oncorhynchus mykiss).
| Content Provider | Semantic Scholar |
|---|---|
| Author | McDonald, M. Danielle Wood, Chris M. |
| Copyright Year | 2004 |
| Abstract | Recent in vivo evidence suggests that the mechanism of branchial urea excretion in the ammoniotelic rainbow trout (Oncorhynchus mykiss) is carrier-mediated. Further characterization of this proposed mechanism was achieved by using an in vitro isolated basolateral membrane vesicle (BLMV) preparation in which isolated gill membranes were used to determine a variety of physiological properties of the transporter. BLMV demonstrated two components of urea uptake, a linear component at concentrations up to 17.5 mmol x l(-1) and a saturable component (K(0.5)=0.35+/-0.01 mmol x l(-1); V(max)=0.14+/-0.02 micromol mg protein(-1) h(-1)) with a Hill constant of 1.35+/-0.18 at low, physiologically relevant urea concentrations (<2 mmol x l(-1)). Saturable uptake of urea at 1 mmol x l(-1) by BLMV was reduced by 88.5% when incubated with 0.25 mmol x l(-1) phloretin, a potent blocker of UT-type facilitated diffusion urea transport mechanisms. BLMV also demonstrated differential handling of urea versus urea analogues at 1 mmol x l(-1) concentrations and total analogue/total urea uptake ratios were 32% for acetamide and 84% for thiourea. Saturable urea uptake at 1 mmol x l(-1) was significantly reduced by almost 100% in the presence of 5 mmol x l(-1) thiourea but was not affected by 5 mmol x l(-1) acetamide or 5 mmol x l(-1) N-methylurea. Lastly, total urea uptake at 1 mmol x l(-1) by BLMV was sensitive to temperatures above and below the temperature of acclimation with a Q(10)>2 suggesting a protein carrier-mediated process. Combined, this evidence indicates that a facilitated diffusion urea transport mechanism is likely present in the basolateral membrane of the rainbow trout gill. |
| Starting Page | 89 |
| Ending Page | 96 |
| Page Count | 8 |
| File Format | PDF HTM / HTML |
| DOI | 10.1016/j.bbamem.2004.02.009 |
| Alternate Webpage(s) | https://www.zoology.ubc.ca/~woodcm/Woodblog/wp-content/uploads/2016/07/McDonald-and-Wood-2004-BBA.pdf |
| PubMed reference number | 15157611 |
| Alternate Webpage(s) | https://doi.org/10.1016/j.bbamem.2004.02.009 |
| Journal | Medline |
| Volume Number | 1663 |
| Issue Number | 1-2 |
| Journal | Biochimica et biophysica acta |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
