Diversity and regulation of amiloride-sensitive Na+ channels.
Amiloride-sensitive Na+ channels play a vital role in many important physiological processes such as delineation of the final urine composition, sensory transduction, and whole-body Na+ homeostasis. These channels display a wide range of biophysical properties, and are regulated by cAMP-mediated second messenger systems. The first of these channels has recently been cloned. This cloned amiloride-sensitive Na+ channel is termined ENaC (Epithelial Na+ Channel) and, in heterologous cellular expression systems, displays a single channel conductance of 4 to 7 pS, a high PNa/PK (> 10), a high amiloride sensitivity (Ki(amil) = 150 nM), and relatively long open and closed times. ENaC may form the core conduction element of many of these functionally diverse forms of Na+ channel. The kinetic and regulatory differences between these channels may be due, in large measure, to unique polypeptides that associate with the core element, forming a functional channel unit.
Benos
D J
DJ
Department of Physiology and Biophysics, University of Alabama at Birmingham, USA.
Awayda
M S
MS
Berdiev
B K
BK
Bradford
A L
AL
Fuller
C M
CM
Senyk
O
O
Ismailov
I I
II
D000584:Amiloride / Q000494:pharmacology*; D000818:Animals; D004232:Diuretics / Q000494:pharmacology*; D006801:Humans; D015222:Sodium Channels / Q000737:chemistry / Q000187:drug effects* / Q000502:physiology*
D004232:Diuretics; D015222:Sodium Channels; D000584:Amiloride