Intracellular potassium activity in mammalian proximal tubule: Effect of perturbations in transepithelial sodium transport

1991 ◽  
Vol 121 (3) ◽  
pp. 249-259 ◽  
Author(s):  
Raynald Laprade ◽  
Jean-Yves Lapointe ◽  
Sylvie Breton ◽  
Marcelle Duplain ◽  
Jean Cardinal
Keyword(s):  
Proximal Tubule ◽  
Sodium Transport ◽  
Intracellular Potassium ◽  
Intracellular Potassium Activity ◽  
Transepithelial Sodium Transport

Intracellular potassium activities in Amphiuma small intestine

1976 ◽  
Vol 231 (4) ◽  
pp. 1214-1219 ◽  
Author(s):  
JF White
Keyword(s):  
Small Intestine ◽  
Membrane Potential ◽  
Activity Coefficient ◽  
Potassium Concentration ◽  
Equilibrium Potential ◽  
Absorptive Cell ◽  
Buffer Solution ◽  
Intracellular Potassium ◽  
Intracellular Potassium Activity ◽  
Liquid Ion Exchanger

Intracellular potassium activity (aKi) has been determined in absorptive cells lining the villi of isolated, stripped proximal segments of Amphiuma small intestine. With single-barreled liquid ion-exchanger microelectrodes aKi = 41.6 +/- 1.5 mM in normal chloride buffer; with double-barreled microelectrodes constructed by a new method aKi = 38.5 +/- 2.4 mM. Also, by the latter approach aKi = 41.1 +/- 2.1 mM in buffer in which potassium was elevated to 5 meq/liter and aKi = 44.2 +/- 1.3 mM in sulfate buffer with the same bath potassium concentration. Since the calculated potassium equilibrium potential exceeds the membrane potential this ion is accumulated by the intestinal absorptive cell. A major portion of cellular potassium is bound or compartmentalized since the intracellular potassium activity coefficient is very low. A layer exists near the villi in which the potassium activity exceeds that in the bath buffer solution.

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