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Pflügers Archiv

, Volume 407, Issue 2, pp 153–157 | Cite as

Influence of potassium depletion on potassium conductance in proximal tubules of frog kidney

  • G. Messner
  • G. Stulnig
  • W. Rehwald
  • F. Lang
Transport Processes, Metabolism and Endocrinology; Kidney, Gastrointestinal Tract, and Exocrine Glands

Abstract

In order to test for the contribution of intracellular potassium activity to the link of sodium/potassium-ATPase activity and potassium conductance, studies with conventional and potassium selective microelectrodes were performed on proximal tubules of the isolated perfused frog kidney. The peritubular transference number for potassium (tk), i.e., the contribution of peritubular slope potassium conductance to the slope conductance of the cell membranes (luminal and peritubular), was estimated from the influence of peritubular potassium concentration on the potential difference across the peritubular cell membrane (PDpt). During control conditions,PDpt is −65±1 mV, intracellular potassium activity (Ki) 57±2 mmol/l andtk 0.41±0.05. The resistance in parallel of the luminal and peritubular cell membranes (Rm) is 44±4 kΩcm, the resistance of the cellular cable (Rc) 137±13 MΩ/cm. When the cells are exposed 10 min to potassium free perfusates (series I),PDpt increases by −28±3 mV within 2 min and then decreases gradually to approach the control value within 10 min.Ki decreases by 22±3 mmol/l andRc increases by 35±10%. After a transient decrease,Rm increases by 36±9%. Readdition of peritubular potassium leads to a transient increase ofPDpt, a gradual decrease ofRm andRc as well as a gradual increase ofKitk recovers only slowly to approach 65±8% of control value within 3 and 79±10% within 6 min. When the cells are exposed 10 min to potassium free perfusates containing 1 mmol/l barium (series II),PDpt depolarizes by +28±4 mV andKi decreases by 7±1 mmol/l within 10 min. Within 2 min of reexposure to control perfusatesPDpt approaches the control value.tk recovers significantly faster than in series I and approaches 92±8% of control value within 3 min and 107±8% within 6 min reexposure to control perfusates. In conclusion, the effect of potassium free perfusates on peritubular potassium conductance depends on the degree of potassium depletion of the cell.

Key words

Potassium depletion Intracellular potassium activity Cell membrane potential Cell membrane resistance Potassium conductance Proximal tubule Amphibian kidney Barium 

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Copyright information

© Springer-Verlag 1986

Authors and Affiliations

  • G. Messner
    • 1
  • G. Stulnig
    • 1
  • W. Rehwald
    • 1
  • F. Lang
    • 1
  1. 1.Institutes of Physiology and Medical PhysicsUniversity of InnsbruckInnsbruckAustria

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