Synchronous transporting activity in epithelial cells in relation to intracellular calcium concentration.
Cultured monolayers of human sweat-gland epithelia have been used to measure electrogenic sodium transport, as short-circuit current, and intracellular Ca2+ concentration ([Ca]i) from Fura-2 fluorescence. The sodium currents in response to the agonists lysylbradykinin, histamine and carbachol show oscillatory behaviour in the 1-2 per minute frequency range. The oscillations can be terminated either by using specific antagonists or with amiloride, which prevents sodium entry into the epithelium. Oscillatory behaviour is also seen when [Ca]i is measured and occurs in the same frequency range. Sodium transport in these cultured epithelia is thought to result from an increase in [Ca]i, which in turn activates calcium-sensitive potassium channels, so increasing the electrochemical gradient for sodium entry. The oscillatory behaviour implies that the epithelial cells behave in synchrony to increase [Ca]i, so inducing synchronous changes in sodium current. It is shown that the behaviour is not unique to sodium-absorbing epithelia, and the possible utility of synchronous behaviour in epithelial tissues is discussed.
Pickles
R J
RJ
Department of Pharmacology, University of Cambridge, U.K.
Brayden
D J
DJ
Cuthbert
A W
AW
D000255:Adenosine Triphosphate / Q000494:pharmacology; D001693:Biological Transport, Active / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D046508:Culture Techniques; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D006632:Histamine / Q000494:pharmacology; D006801:Humans; D007424:Intracellular Fluid / Q000378:metabolism; D007609:Kallidin / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism*; D013545:Sweat Glands / Q000187:drug effects / Q000378:metabolism*
D007609:Kallidin; D006632:Histamine; D000255:Adenosine Triphosphate; D002217:Carbachol; D012964:Sodium; D002118:Calcium