Measuring gill paracellular permeability with polyethylene glycol-4000 in freely swimming trout: proof of principle

摘要: The influence of swimming activity on gill paracellular permeability has not been measured previously in fishes. We critically assessed the use tritium-labeled polyethylene glycol ([3H]PEG-4000) for this purpose, a substance that is also classic marker extracellular fluid volume, glomerular filtration rate and drinking rate. Tests (8 h) resting freshwater trout showed when measuring [3H]PEG-4000 clearance from plasma efflux direction, correction large excretion via was essential, necessitating urinary catheterization. When water influx significant uptake by terminal gut removal, whereas losses were minimal. After these alternate routes loss uptake, rates identical, showing rectified, can be either direction. technique with removal used to assess without catheters freely at 1.2 body lengths s−1 8 h. Branchial (by water) increased significantly ~80% accord similar increase O2 consumption Thus trout, does during exercise, traditional concept osmorespiratory compromise.