|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
Journal of Experimental Biology, Vol 196, Issue 1 405-418, Copyright © 1994 by Company of Biologists
JOURNAL ARTICLES |
JR Riordan, B Forbush and JW Hanrahan
Hospital for Sick Children, Toronto, Ontario, Canada.
Transepithelial Cl- secretion in vertebrates is accomplished by a secondary active transport process brought about by the coordinated activity of apical and basolateral transport proteins. The principal basolateral components are the Na+/K(+)-ATPase pump, the Na+/K+/2Cl- cotransporter (symporter) and a K+ channel. The rate-limiting apical component is a cyclic-AMP-stimulated Cl- channel. As postulated nearly two decades ago, the net Cl- movement from the blood to the lumen involves entry into the epithelial cells with Na+ and K+, followed by active Na+ extrusion via the pump and passive K+ exit via a channel. Intracellular [Cl-] is raised above electrochemical equilibrium and exits into the lumen when the apical Cl- channel opens. Cl- secretion is accompanied by a passive paracellular flow of Na+. The tubules of the rectal glands of elasmobranchs are highly specialized for secreting concentrated NaCl by this mechanism and hence have served as an excellent experimental model in which to characterize the individual steps by electrophysiological and ion flux measurements. The recent molecular cloning and heterologous expression of the apical Cl- channel and basolateral cotransporter have enabled more detailed analyses of the mechanisms and their regulation. Not surprisingly, since hormones acting through kinases control secretion, both the Cl- channel, which is the shark counterpart of the CFTR (Cystic Fibrosis Transmembrane Conductance Regulator), and the cotransporter are regulated by phosphorylation and dephosphorylation. The primary stimulation of secretion by hormones employing cyclic AMP as second messenger activates CFTR via the direct action of protein kinase A (PKA), which phosphorylates multiple sites on the R domain. In contrast, phosphorylation of the cotransporter by as yet unidentified kinases is apparently secondary to the decrease in intracellular chloride concentration caused by anion exit through CFTR.
This article has been cited by other articles:
|
|
 |
|
  T. J. Shuttleworth, J. Thompson, R. S. Munger, and C. M. Wood A critical analysis of carbonic anhydrase function, respiratory gas exchange, and the acid-base control of secretion in the rectal gland of Squalus acanthias J. Exp. Biol., December 1, 2006; 209(23): 4701 - 4716. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. J. Walsh, M. Kajimura, T. P. Mommsen, and C. M. Wood Metabolic organization and effects of feeding on enzyme activities of the dogfish shark (Squalus acanthias) rectal gland J. Exp. Biol., August 1, 2006; 209(15): 2929 - 2938. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. J. Weber, A. P. Mehr, J. C. Sirota, S. G. Aller, S. E. Decker, D. C. Dawson, and J. N. Forrest Jr. Mercury and zinc differentially inhibit shark and human CFTR orthologues: involvement of shark cysteine 102 Am J Physiol Cell Physiol, March 1, 2006; 290(3): C793 - C801. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. H. Evans, P. M. Piermarini, and K. P. Choe The Multifunctional Fish Gill: Dominant Site of Gas Exchange, Osmoregulation, Acid-Base Regulation, and Excretion of Nitrogenous Waste Physiol Rev, January 1, 2005; 85(1): 97 - 177. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. R. Scott, J. G. Richards, B. Forbush, P. Isenring, and P. M. Schulte Changes in gene expression in gills of the euryhaline killifish Fundulus heteroclitus after abrupt salinity transfer Am J Physiol Cell Physiol, August 1, 2004; 287(2): C300 - C309. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. P. Wallace, L. A. Rome, L. P. Sullivan, and J. J. Grantham cAMP-dependent fluid secretion in rat inner medullary collecting ducts Am J Physiol Renal Physiol, June 1, 2001; 280(6): F1019 - F1029. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Evans and P. Piermarini Contractile properties of the elasmobranch rectal gland J. Exp. Biol., January 1, 2001; 204(1): 59 - 67. [Abstract] [PDF]
|
|
|
|
|
|
P. Piermarini and D. Evans Effects of environmental salinity on Na(+)/K(+)-ATPase in the gills and rectal gland of a euryhaline elasmobranch (Dasyatis sabina) J. Exp. Biol., January 10, 2000; 203(19): 2957 - 2966. [Abstract] [PDF]
|
|
|
|
|
|
S. C. Jacoby, E. Gagnon, L. Caron, J. Chang, and P. Isenring Inhibition of Na+-K+-2Cl- cotransport by mercury Am J Physiol Cell Physiol, October 1, 1999; 277(4): C684 - C692. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. F. Husted, C. Zhang, and J. B. Stokes Concerted actions of IL-1beta inhibit Na+ absorption and stimulate anion secretion by IMCD cells Am J Physiol Renal Physiol, December 1, 1998; 275(6): F946 - F954. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. M. Breen, P. J. Mannon, and B. A. Benjamin Peptide YY inhibits vasopressin-stimulated chloride secretion in inner medullary collecting duct cells Am J Physiol Renal Physiol, September 1, 1998; 275(3): F452 - F457. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. D. Singer, S. J. Tucker, W. S. Marshall, and C. F. Higgins A divergent CFTR homologue: highly regulated salt transport in the euryhaline teleost F. heteroclitus Am J Physiol Cell Physiol, March 1, 1998; 274(3): C715 - C723. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. AGUILAR-BRYAN, J. P. CLEMENT IV, G. GONZALEZ, K. KUNJILWAR, A. BABENKO, and J. BRYAN Toward Understanding the Assembly and Structure of KATP Channels Physiol Rev, January 1, 1998; 78(1): 227 - 245. [Abstract] [Full Text] [PDF]
|
|
