In vitro studies of theophylline-induced changes in Na, K and Cl transport in hen (Gallus domesticus) colon suggesting bidirectional, basolateral NaK2Cl cotransport.
1. In isolated mucosa from a NaCl-loaded hen theophylline stimulates both unidirectional chloride fluxes (JmsCl and JsmCl). Conductive and electroneutral exchange processes, besides a bumetanide-sensitive, rheogenic process contribute. 2. The bumetanide-sensitive fraction of the theophylline-induced delta JcmCl is sodium-dependent. 3. Incubation in nominally K(+)-free solutions reduces the bumetanide-sensitive fraction delta JsmCl more than treatment with ouabain. 4. With respect to chloride the bumetanide-sensitive fraction of delta JsmCl has a Hill coefficient of 1.93 +/- 0.03, a Jmax of 12.9 +/- 0.2 mumol/cm2.hr and a K 1/2 of 73 +/- 1 mmol/l. 5. After ouabain treatment delta JmsCl and delta JsmCl are equally sensitive to bumetanide, while delta JmsCl is bumetanide insensitive without ouabain treatment.
Andersen
V
V
Department of General Physiology and Biophysics, Panum Institute, University of Copenhagen, Denmark.
Munck
B G
BG
Munck
L K
LK
Skadhauge
E
E
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002034:Bumetanide / Q000494:pharmacology; D002645:Chickens / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism*; D003106:Colon / Q000378:metabolism; D005260:Female; D007413:Intestinal Mucosa / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D013806:Theophylline / Q000494:pharmacology*
D002712:Chlorides; D002034:Bumetanide; D012964:Sodium; D013806:Theophylline; D011188:Potassium