P. Silva et al., TRANSPORT MECHANISMS THAT MEDIATE THE SECRETION OF CHLORIDE BY THE RECTAL GLAND OF SQUALUS-ACANTHIAS, The Journal of experimental zoology, 279(5), 1997, pp. 504-508
The rectal gland of Squalus acanthias secretes chloride by a mechanism
that has been termed ''secondary active transport'' because it depend
s on the activity of Na-K-ATPase. As currently described, chloride ent
ers the cell across the basolateral cell membrane via the 2 chloride:
sodium: potassium cotransporter. The energy for this electroneutral up
hill movement of chloride and potassium is provided by the gradient fo
r sodium directed into the cell. Present in the basolateral cell membr
ane is Na-K-ATPase that maintains the gradient for sodium. A potassium
conductance, present as well in the basolateral cell membrane, recirc
ulates the potassium. Chloride exits the cell across the luminal membr
ane via CFTR, the chloride conductance. This mechanism is widely distr
ibuted throughout vertebrates. This report reviews the experimental ob
servations that led to the current definition of the mechanism of chlo
ride transport in the rectal gland. (C) 1997 Wiley-Liss, Inc.