Effects of alkalosis on skeletal muscle metabolism and performance during exercise

Am J Physiol. 1986 Nov;251(5 Pt 2):R833-9. doi: 10.1152/ajpregu.1986.251.5.R833.


This study examined the effects of extracellular alkalosis on the metabolism and performance of perfused rat hindlimb muscles during electrical stimulation. Three acid-base conditions were used: control (C, normal acid-base state), metabolic alkalosis (MALK, increased bicarbonate concentration), and respiratory alkalosis (RALK, decreased PCO2). A one-pass system was used to perfuse the hindlimb via the femoral artery for 20 min at rest and during 5 min of tetanic stimulation via the sciatic nerve. The isometric tension generated by the gastrocnemius-plantaris-soleus muscle group was recorded. Arterial and venous perfusates were periodically sampled for substrate and metabolite measurements, and muscle samples were taken pre- and postperfusion. Peak isometric tensions in C, MALK, and RALK were similar: 3,367 +/- 107, 3,317 +/- 110, and 3,404 +/- 69 g, respectively. The rate of tension decay was also unaffected by alkalosis and represented 78 and 55% of the peak tension following 2 and 5 min of stimulation, respectively. Muscle O2 uptake, glycogen utilization, and total lactate (La-) production were similar following 5 min of stimulation in all conditions. However, alkalosis resulted in an enhanced La- release from working muscle (peak La- release: C, 15.5 +/- 1.1; MALK, 19.7 +/- 1.6; RALK, 18.3 +/- 2.2 mumol/min), and a 15-20% reduction in intramuscular La- accumulation. Alkalosis had no effect on muscle creatine phosphate and ATP concentrations. Thus, in the perfused rat hindlimb, alkalosis was not associated with changes in tetanic force or glycolysis, but La- release from the working muscle was enhanced by increased extracellular pH and bicarbonate.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkalosis / metabolism*
  • Alkalosis / physiopathology
  • Animals
  • Glucose / metabolism
  • Glycogen / metabolism
  • Isometric Contraction
  • Lactates / metabolism
  • Lactic Acid
  • Male
  • Muscles / metabolism*
  • Muscles / physiopathology
  • Oxygen Consumption
  • Physical Exertion*
  • Rats
  • Rats, Inbred Strains


  • Lactates
  • Lactic Acid
  • Glycogen
  • Glucose