Pflügers Archiv

, Volume 401, Issue 2, pp 119–124

O2 consumption, aerobic glycolysis and tissue phosphagen content during activation of the NA+/K+ pump in rat portal vein

  • Per Hellstrand
  • Carin Jorup
  • Marie-Louise Lydrup
Excitable Tissues and Central Nervous Physiology

DOI: 10.1007/BF00583871

Cite this article as:
Hellstrand, P., Jorup, C. & Lydrup, ML. Pflugers Arch. (1984) 401: 119. doi:10.1007/BF00583871

Abstract

Oxygen consumption, lactate production and tissue contents of ATP, phosphocreatine (PCr) and lactate were measured following readdition of K+ to K+-depleted rat portal veins, in order to study the energy turnover associated with Na+/K+ pumping. During incubation in K+-free medium at 37° C spontaneous contractions disappeared in 10–20 min. Readdition of K+ (5.9 mM) after 40 min K+-free incubation caused hyperpolarization of the cell membrane for the first 5–10 min and then gradual depolarization with return of spontaneous action potentials and contractions by 10–20 min. During the first 4–6 min after K+ readdition aerobic lactate production was about doubled and then gradually returned to the original level (0.17 μmol/min g) at about 20 min. The increase in glycolytic rate was prevented by 1 mM ouabain. In contrast, O2 consumption (in K+-free medium, 0.38 μmol/min g) rose by about 10% when K+ was added and this increase lasted about 5 min. By 8 min after K+ addition the increased glycolysis and oxidative phosphorylation had accounted for each about the same amount of extra ATP generation over that extrapolated from the steady rate before K+ addition. The average total increase in ATP turnover in the first 8 min was 15%. During this period there was no change in the cellular content of ATP, PCr, or extractable ADP. The results indicate that Na+/K+ pumping utilizes a relatively small share of the total energy turnover in the vascular smooth muscle but is to a large extent dependent on aerobic glycolysis and therefore a major site of carbohydrate usage.

Key words

Vascular smooth muscle Na+/K+ pump, O2 consumption Glycolysis Membrane potential 

Copyright information

© Springer-Verlag 1984

Authors and Affiliations

  • Per Hellstrand
    • 1
  • Carin Jorup
    • 1
  • Marie-Louise Lydrup
    • 1
  1. 1.Department of Physiology and BiophysicsUniversity of LundLundSweden

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