A basolateral K+ conductance modulated by carbachol dominates the membrane potential of small intestinal crypts.
The contribution of possible ionic conductances to the membrane potential (Em) of cells in guinea-pig small intestinal crypts has been studied using the nystatin "perforated-patch" approach in current-clamp experiments. Changes in extracellular K+ produced shifts in Em, with a 37 mV change in potential per ten-fold increase in extracellular K+ concentration. Reduction of extracellular Cl- by 130 mM led to a 7 mV hyperpolarisation while Na+ replacement was without effect on Em. The muscarinic agonist carbachol produced a hyperpolarisation which could be ascribed to an increase in basolateral K+ conductance. This effect was sustained in the presence of extracellular Ca2+ but was transient in its absence. We conclude that the conductance of the basolateral membrane of small intestinal crypts is mainly K+ selective and can be reversibly increased by muscarinic activation.
Walters
R J
RJ
AFRC Institute of Animal Physiology and Genetics Research, Babraham, Cambridge, UK.
Sepúlveda
F V
FV
D000818:Animals; D002217:Carbachol / Q000494:pharmacology*; D007421:Intestine, Small / Q000378:metabolism*; D008564:Membrane Potentials; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D051381:Rats
D015221:Potassium Channels; D002217:Carbachol; D011188:Potassium