Potassium channels in epithelial transport.
Epithelial cells in the kidney, gastrointestinal tract and exocrine glands are engaged in vectorial transport of salt and nutrients. In these tissues, K(+) channels play an important role for the stabilization of membrane voltage and maintenance of the driving force for electrogenic transport. Luminal K(+) channels represent an exit pathway for the excretion of K(+) in secreted fluid, urine and faeces, thereby effecting body K(+) homeostasis. Indeed, the expression and function of several luminal K(+) channels is modulated by hormones regulating water, Na(+), and K(+) metabolism. In addition to net transport of K(+) in the serosal (or apical) direction, K(+) channels can be coupled functionally to K(+)-transporting ATPases such as the basolateral Na(+)/K(+) ATPase or the luminal H(+)/K(+) ATPase. These ATPases export Na(+) or H(+) and take up K(+), which is then recycled via K(+) channels. This review gives a short overview on the molecular identity of epithelial K(+) channels and summarizes the different mechanisms of K(+) channel function during transport in epithelial cells.
Warth
Richard
R
Physiologisches Institut, Winterthurerstrasse 190, 8057 Zürich, Switzerland. warthri@physiol.unizh.ch
D000818:Animals; D001692:Biological Transport / Q000502:physiology; D004847:Epithelial Cells / Q000378:metabolism*; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D015221:Potassium Channels / Q000378:metabolism*
D015221:Potassium Channels