... that these cells play a combined glutamine production and urea excretion role, which may have implications for predator avoidance. * Author for correspondence (e-mail: dmcdonald@rsmas.miami.edu ) 11 12 2008 2009 facilitated diffusion urea production urea excretion stress cortisol...

.... However, the conditions at the low-pressure boundary, the mitochondrial–sarcoplasmic interface, have resisted experimental enquiry. These conditions cannot be predicted from the equations of facilitated diffusion and are required for analytic solution of those equations. Knowledge of the conditions...

... found in photobleaching experiments (1.2×10 -7 cm 2 s -1 at 22°C or 2.1×10 -7 cm 2 s -1 at 37°C) is about one-tenth that in dilute solution(11.3×10 -7 cm 2 s -1 at 20°C) and about one-fifth that often used in earlier calculations of the magnitude of facilitated diffusion. The identical values...

... permeability; and (iii) the presence of a specific facilitated diffusion transport system that is periodically activated. Exposure of toadfish during non-pulse periods to treatments designed to block a ‘back-transport’ mechanism (Na + -free sea water or the urea analogues 30 mmol l −1 thiourea or 30 mmol l −1...