Measurement of potassium absorption during hypokinesia in potassium supplemented and unsupplemented healthy subjects

Abstract

Measuring potassium (K+) absorption, and K+ levels in plasma, urine and feces during and after hypokinesia (HK) and K+ supplementation, the aim of this study was to determine if prolonged HK could depress K+ deposition significantly more with or without K+ supplementation. Studies were conducted during 30-days pre-HK, 364-days HK and 30-days post-HK. Forty male healthy volunteers 24.2+/-5.5 years of age were chosen as subjects. They were equally divided in four groups: unsupplemented active control subjects (UACS), unsupplemented hypokinetic subjects (UHKS), supplemented active control subjects (SACS), and supplemented hypokinetic subjects (SHKS). Hypokinetic subjects were walking average distances of 0.5+/-0.2 km day(-1). Active control subjects were running average distances of 5.8+/-1.2 km day(-1). Both SHKS and SACS consumed daily 2.17 mEq elemental potassium per kg body weight. Potassium absorption, fecal and urinary K+ excretion, sodium (Na+) loss, plasma K+ and Na+ level and plasma aldosterone (PA) level did not change in SACS and UACS compared with their pre-HK values. During HK, K+ absorption decreased significantly (P < 0.05) with time, and fecal and urinary K+ loss, urinary Na+ loss, plasma K+ and Na+ levels and PA level increased significantly (P < 0.05) with time in SHKS and UHKS compared with their pre-HK values and their respective active controls (SACS and UACS). During initial 15-days of post-HK, K+ absorption increased significantly (P < 0.05), fecal and urinary K+ excretion, urinary Na+ excretion and plasma K+ and Na+ levels and PA level decreased significantly (P < 0.05) in hypokinetic compared with active control subjects; by the 30th day they approached the control levels. During HK and post-HK, K+ absorption, fecal and urinary K+ losses, urinary Na+ excretion, plasma K+ and Na+ levels and PA level, changed significantly (P < 0.05) more in SHKS than UHKS. Decreased K+ losses during post-HK showed K+ depletion during HK. Decreased K+ absorption with K+ depletion during HK showed decreased K+ deposition. The greater K+ changes in SHKS than UHKS, during HK and post-HK, demonstrated that K+ deposition decreased more with than without K+ supplementation. It was concluded that dissociation between K+ absorption and K+ depletion showed decreased K+ deposition as the main mechanism for K+ depletion during HK.

Inability of healthy subjects to deposit potassium during hypokinesia and potassium supplementation

“…It is consistent with prior studies [11][12][13][14] where during the preexperimental period, K + homeostasis, plasma K + level, and urine and fecal K + loss were relatively stable regardless of the amount of K + consumed. This shows that in the pre-experimental period, the K + consumed during supplementation has been used up for deposition and was taken by the body which protected the net muscle K + content, plasma K + level, and urine and fecal K + loss without showing any gross differences in the experimental and control groups of subjects.…”

Mechanism of sodium loss with muscle sodium deficiency in sodium supplemented and unsupplemented subjects during hypokinesia

“…This is consistent with previous studies (10)(11)(12)(13) whereby, during the pre-experimental period the electrolyte metabolism was relatively stable regardless of the electrolyte consumption. This is consistent with previous studies (10)(11)(12)(13) whereby, during the pre-experimental period the electrolyte metabolism was relatively stable regardless of the electrolyte consumption.…”

Muscle Potassium and Potassium Losses During Hypokinesia in Healthy Subjects

“…The level of plasma magnesium, phosphate, calcium, potassium (K + ), sodium and chloride, and electrolyte losses increases [10][11][12][13] and tissue electrolyte content decreases [5][6][7][8][9]. The higher plasma electrolyte level and electrolyte losses and the lower tissue electrolyte content are related to many factors inherently to prolonged HK [5][6][7][8][9][10][11][12][13].…”

“…The higher plasma electrolyte level and electrolyte losses and the lower tissue electrolyte content are related to many factors inherently to prolonged HK [5][6][7][8][9][10][11][12][13]. The higher plasma electrolyte concentration and electrolyte losses and the lower tissue electrolyte content indicate less efficient electrolyte deposition; this usually contributes to the electrolyte losses in electrolyte-deficient tissue [5][6][7][8][9].…”

“…The higher plasma electrolyte concentration and electrolyte losses and the lower tissue electrolyte content indicate less efficient electrolyte deposition; this usually contributes to the electrolyte losses in electrolyte-deficient tissue [5][6][7][8][9]. The higher plasma electrolyte level and electrolyte losses in electrolyte-deficient tissue indicate different kind of mechanisms from those associated with decreased plasma electrolyte level and electrolyte losses in electrolyte-deficient tissue during normal muscular activity [5][6][7][8][9][10][11][12][13].…”