Potassium-induced cell swelling in Necturus gallbladder epithelium.
In Necturus gallbladder epithelium, elevation of mucosal K+ to 95 mM in the presence of 10 mM Na+ resulted in cell swelling at a rate of 3.2% original volume per minute, followed by volume-regulatory shrinking. When Na+ was completely removed from or when amiloride (10(-4) M) was added to the mucosal medium, K+-induced cell swelling was abolished. In the presence of 10 mM Na+, 1 mM Ba2+ abolished and substitution of mucosal Cl- by NO-3 had no effect on K+-induced swelling. Thus solute entry following elevation of mucosal K+ is effected by separate K+ and Cl- pathways. Furthermore, substitution of 95 mM K+ for Na+ in the mucosal bathing medium leads to the development of a Cl- conductance in the basolateral membrane as long as some Na+ remains in the medium. However, cell swelling induced by mucosal dilution does not lead to the appearance of a Cl- conductance. Thus the activation of this conductance requires both swelling and membrane depolarization. These results show that 1) high mucosal K+ leads to cell swelling due to the entry of Cl- along with K+ and the Cl- can enter across either membrane, 2) the Cl- pathways require the presence of mucosal Na+, and 3) cell volume regulation is activated by an increase in volume per se, i.e., a hyposmotic exposure is not required for volume regulation to occur.
D000818:Animals; D001464:Barium / Q000378:metabolism; D002462:Cell Membrane / Q000502:physiology; D002712:Chlorides / Q000378:metabolism; D003494:Cyclamates / Q000378:metabolism; D004553:Electric Conductivity; D004594:Electrophysiology; D004848:Epithelium / Q000187:drug effects / Q000502:physiology; D005704:Gallbladder / Q000187:drug effects*; D009337:Necturus; D009609:Nitrous Oxide / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology*; D012016:Reference Values
D002712:Chlorides; D003494:Cyclamates; D001464:Barium; D009609:Nitrous Oxide; D011188:Potassium