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

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.