Nuclear size measurements in collecting tubules of the rat kidney in establishing the effect of hypokinesia on the kidney morphology.

BACKGROUND: Hypokinesia (reduced motor activity) induces significant tissue morphological changes, however, it is not known if hypokinesia (HK) could contribute to morphological changes in the kidney. Measuring the nuclear size in the inner medullary collecting ducts on the kidney of rats the aim of this investigation was to disclose kidney morphological changes during prolonged HK. METHODS: Studies were done on 192 13-week-old male rats (370 to 390 g) during 15 days pre-HK period and 90 days HK period. Rats were equally divided into 2 groups: vivarium control rats (VCR) and hypokinetic rats (HKR). All HKR were kept in small individual cages. RESULTS: A significant (p<0.05) increase in size of collecting duct nuclei of the kidney, plasma aldosterone (PA), plasma and urinary Sodium (Na) and Potassium (K) and fluid loss, a significant (p<0.05) decrease of fluid intake, body weight and plasma antidiuretic hormone (ADH) observed in HKR when compared with their pre-HK values and the values in VCR. The measured parameters change insignificantly (p>0.05) in VCR when compared with their pre-HK values. CONCLUSIONS: It was concluded that the nuclear size in the inner medullary collecting ducts of the kidney increases significantly during prolonged HK. The reason for this reaction remains unclear.

Phosphate measurements during hypokinesia and phosphate supplements in disclosing phosphate changes in hypokinetic subjects.

BACKGROUND: Hypokinesia (diminished movement) induces significant phosphate (P) change, however, little is known about P retention and P depletion during hypokinesia (HK). Measuring P retention and P balance during HK and P supplementation, the objective of this work was to disclose whether HK could contribute to the decreased P retention and consequently to P depletion in normal subjects. METHODS: Studies were done during 30 days pre-HK period and 364 days HK period. Forty normal male individuals aged, 25.3+/-6.4 years were chosen as subjects. They were divided equally into 4 groups: unsupplemented active control subjects (UACS), unsupplemented hypokinetic subjects (UHKS), supplemented active control subjects (SACS) and supplemented hypokinetic subjects (SHKS). Hypokinetic subjects were limited to an average walking distance of 0.5 km day-l, while active control subjects were kept on an average running distance of 9.6 km day-l. Both, SHKS and SACS received daily 14 mmol dicalcium phosphate per kg body weight. RESULTS: Negative P balance, fecal P, urinary calcium (Ca) and P excretion, serum P and total (Cat) level increased significantly (p<0.05) while P retention, serum intact parathyroid hormone (iPTH), 1,25 dihydroxyvitamin D (1,25 (OH)2 D3) and thyrocalcitonin (TC) decreased significantly (p<0.05) in SHKS and UHKS compared with their pre-HK values and their respective active controls (SACS and UACS). However, negative P balance, P retention incapacity, serum, fecal and urinary P level increased significantly (p<0.05) more in SHKS compared with UHKS. Fecal P loss, urinary P and Ca loss, serum P and Cat level, iPTH, TC and 1,25 (OH)2 D3 level, P retention and P balance change insignificantly (p>0.05) in SACS and UACS compared with their pre-HK level. CONCLUSIONS: It was concluded that a significant P excretion in urine and feces in spite of negative P balance and P supplementation may demonstrate reduced P retention, while a significant increase of negative P balance may demonstrate P depletion. Clearly, P intake, regardless of its low or higher dose, was significantly wasted during HK probably due to the decreased ability of the body to retain P.

Measurements of nuclear size in collecting tubules of the kidney of rats during prolonged hypokinesia and ambulatory conditions.

Hypokinesia (decreased motor activity) induces significant morphological changes in the kidneys, but little is known about the effect of hypokinesia (HK) on the collecting duct nuclei of the kidney. The aim of this study was to measure the effect of prolonged HK on the nuclear size in the inner meduallary collecting ducts on the kidney of rats. Studies were done on one hundred ninety-two 13-week-old male rats (370 to 390 g) during 15 days pre HK period and 90 days HK period. Rats were equally divided into two groups: vivarium control rats (VCR) and hypokinetic rats (HKR). The HKR group kept in small individual cages. Nuclear size in renal collecting tubules, fluid excretion, sodium (Na) and potassium (K) in plasma and urine, plasma aldosterone (PA) and antidiuretic hormone (ADH) and body weight were measured. A significant (p < or = 0.01) increase in size of the collecting duct nuclei of the kidney, PA, plasma and urinary Na and K and fluid loss, and a significant (p < or = 0.01) decrease of body weight and plasma ADH observed in the HKR group when compared with the VCR. The measured parameters did not change significantly in the VCR group when compared with their baseline control values. It was concluded that prolonged HK induces a significant increase of the nuclear size in the inner meduallary collecting ducts of the kidney of hypokinetic rats when compared with the control rats.

Measurements in calcium-supplemented athletes during and after hypokinetic and ambulatory conditions.

STUDY OBJECTIVE: Hypokinesia (diminished movement) induces significant calcium (Ca) changes, however, little is known about Ca deficiency during hypokinesia (HK). By using Ca supplements during and after HK, the aim of this study was to establish whether HK could contribute to Ca deficiency. DESIGN AND METHODS: Studies were done during the pre-HK period of 30 days, HK period of 364 days and post-HK period of 30 days. Forty male trained athletes aged, 25.0 +/- 7.7 yr were chosen as subjects. They were equally divided into four groups: unsupplemented ambulatory control subjects (UACS), unsupplemented hypokinetic subjects (UHKS), supplemented ambulatory control subjects (SACS), and supplemented hypokinetic subjects (SHKS). The SHKS and SACS groups took daily 55.0 mg elemental Ca per kg body weight. Hypokinetic subjects were limited to an average walking distance of 0.7 km/day, while the control subjects were running 11.6 km/day. RESULTS: Fecal Ca, urinary Ca, and urinary phosphate (P) excretion, serum ionized calcium (Ca(I)), P and total Ca levels, intact parathyroid hormone (iPTH), 1,25 dihydroxyvitamin D (1,25(OH)(2)D(3)), fluid and food intakes, peak oxygen uptake, and physical characteristics were measured. During HK fecal Ca, urinary Ca, and urinary P excretion and serum P, Ca(I), and Ca level increased significantly (p < or = 0.01), whereas during the initial days of post-HK decreased significantly (p < or = 0.01) in the SHKS and unsupplemented hypokinetic subjects groups when compared with the SACS and UACS groups, respectively. During HK serum 1,25(OH)(2)D(3), iPTH levels, food and fluid intakes, body weight, body fat, and peak oxygen uptake decreased significantly (p < or = 0.01), while during the initial days of post-HK remained significantly (p < or = 0.01) depressed and fluid intakes increased significantly (p < or = 0.01) in the SHKS and unsupplemented hypokinetic subjects groups when compared with SACS and UACS groups, respectively. Serum, urinary and fecal Ca changed much more in the SHKS than UHKS. Serum, fecal, and urinary minerals, iPTH, 1,25(OH)(2)D(3) levels, food and fluid intakes, body weight, body fat, and peak oxygen uptake did not change markedly in the SACS and UACS groups when compared with their baseline values. CONCLUSION: It was shown that serum Ca concentration, urinary, and fecal Ca excretion increased during HK and decreased significantly during post-HK. Oral Ca supplementation did not significantly affect serum Ca levels or urinary and fecal Ca loss. It was concluded that decreased urinary and fecal Ca loss during post-HK, may suggest the presence of Ca deficiency during prolonged HK.

Calcium supplementation effect on calcium balance in endurance-trained athletes during prolonged hypokinesia and ambulatory conditions.

Calcium (Ca) supplements may be used to normalize Ca-balance changes but little is known about the effect of Ca supplements on Ca balance during hypokinesia (decreased kilometers per day). The aim of this study was to evaluate the effect of daily intakes of Ca supplements on Ca balance during hypokinesia (HK). Studies were done during 30 d of a pre-HK period and during 364 d of a HK period. Forty male athletes aged 23-26 yr were chosen as subjects. They were divided equally into four groups: unsupplemented ambulatory control subjects (UACS), unsupplemented hypokinetic subjects (UHKS), supplemented hypokinetic subjects (SHKS), and supplemented ambulatory control subjects (SACS). The SHKS and UHKS groups were kept under an average running distance of 0.7 km/d. In the SHKS and SACS groups supplemented with 35.0 mg Ca lactate/kg body weight. Fecal Ca loss, urinary excretion of Ca and phosphate (P), serum concentrations of ionized calcium (CaI) total Ca, P, and Ca balance, intact parathyroid hormone (iPTH) and 1,25 dihydroxyvitamin D (1,25(OH)2D), anthropometric characteristics and peak oxygen uptake were measured. Fecal Ca excretion, urinary Ca and P excretion, serum CaI, total Ca, and P concentration, and negative Ca balanced increased significantly (p < or = 0.01) in the SHKS and UHKS groups when compared with the SACS and UACS groups. Serum, urinary, and fecal Ca changes were much greater and appeared much faster in the SHKS group than in the UHKS group. Serum iPTH and 1,25 (OH)2 D, body weight, and peak oxygen uptake decreased significantly (p < or = 0.01) in the SHKS and UHKS groups when compared with the SACS and UACS groups. In contrast, the corresponding parameters remained stable in the SACS and UACS groups when compared with the baseline control values. It was concluded that during prolonged HK, urinary and fecal Ca excretion and serum Ca concentration increased significantly despite the presence of a negative Ca balance; thus, Ca supplements cannot be used to normalize negative Ca balance during prolonged HK.

Calcium measurements in primates during and after hypokinesia in establishing calcium deficiency during prolonged hypokinesia.

Hypokinesia (diminished movement) induces significant calcium (Ca) changes, but little is known about the effect of hypokinesia (HK) on Ca deficiency. Measuring Ca changes during and after HK the aim of this study was to determine Ca deficiency during prolonged HK. Studies were done on 12 male Macaca mulatta (rhesus monkeys) aged 3-5 yr (5.58-6.42 kg) during a 90-d pre-HK period, a 90-d HK period, and a 15-d post-HK period. Monkeys were equally divided into two groups: vivarium control monkeys (VCM) and hypokinetic monkeys (HKM). Hypokinetic monkeys were kept in small individual cages that restricted their movements in all directions without hindering food and water intakes. Urinary, fecal, and serum Ca, urinary and serum magnesium (Mg) and phosphate (P), serum intact parathyroid hormone (iPTH), and calcitonin (CT) concentration, body weight, food intake, fluid consumed and eliminated in urine were measured. During the HK period, fecal Ca loss, urinary Ca, P, and Mg excretion, fluid elimination, and serum P, Ca, and Mg concentration increased significantly (p < or = 0.01), whereas serum iPTH and CT concentration, food and fluid intakes, and body weight decreased significantly (p < or = 0.01) in the HKM group when compared with the VCM group. During the initial days of the post-HK period, serum Ca, Mg, and P concentration, fecal Ca loss, urinary Ca, Mg, and P excretion, and fluid elimination decreased significantly (p < or = 0.01), whereas fluid intake increased significantly (p < or = 0.01) in the HKM group when compared with the VCM group. Food intake, body weight, and serum iPTH and CT concentrations remained significantly (p < or = 0.01) depressed in the HKP group when compared with the VCM; however, they increased as the duration of the post-HK period increased. By contrast, the corresponding parameters remained stable in the VCM group when compared with the baseline control values. It was shown that fecal and urinary Ca loss and serum Ca concentration increases significantly during HK, whereas during postHK fecal, urinary, and serum Ca decreases significantly. It was concluded that significant decrease of serum, urinary, and fecal Ca during post-HK may suggest the presence of Ca deficiency during prolonged HK.

Plasma, urinary and fecal potassium changes in athletes during ambulatory, periodic, and continuous hypokinetic conditions.

OBJECTIVES: Prolonged hypokinesia (HK) induces significant electrolyte changes, but little is known about the effect of prolonged periodic hypokinesia on plasma, urinary, and fecal K. The aim of this study was to measure potassium (K) changes during prolonged periodic (PHK) and continuous (CHK). DESIGN AND METHODS: Studies were done during the pre HK and HK periods. Thirty male athletes were chosen as subjects. They were divided equally into three groups: unrestricted ambulatory control subjects (UACS), continuously hypokinetic subjects (CHKS), and periodically hypokinetic subjects (PHKS). The CHKS group was kept on a running distance of 0.7 km/day, while the PHKS group kept on a running distance of 0.7 and 11.7 km/day for 5 days and 2 days per week, respectively. The UACS group was on a running distance of 11.7 km/day. RESULTS: The following were measured: fecal K excretion; urinary K; sodium (Na) and chloride (CI) excretion; plasma K; Na and CI concentration; plasma renin activity (PRA) and plasma aldosterone (PA) concentration; physical characteristics; and peak oxygen uptake. Fecal K, urinary K, Na and CI excretion, plasma K, Na and CI concentration, and PRA and PA concentration, increased significantly (p< or =0.01) in the CHKS and PHKS groups when compared with the UACS group. Body weight and VO2 peak decreased significantly (p< or =0.01) in the CHKS group, while body weight increased and VO2 peak decreased significantly (p< or =0.01) in the PHKS group when compared with the UACS group. The measured parameters changed much more in the PHKS group than in the CHKS group. By contrast, the measured parameters did not change significantly in the UACS group when compared with the baseline control values. CONCLUSION: It was shown that prolonged PHK and CHK induce significant plasma and excretory K changes; however, plasma and excretory K changes were much greater in the PHKS group than in the CHKS group. It was concluded that the greater the stability of muscular activity, the smaller the plasma, urinary, and fecal K changes during prolonged HK.

Electrolytes in femur and plasma of rats during prolonged restriction of motor activity.

Hypokinesia (decreased motor activity) induces insignificant bone mineral changes. The aim of this study was to measure mineralization, density, and also electrolyte content in the femur of rats during prolonged hypokinesia (HK). Studies were done on 144 male Wistar rats (370-390 g) during 15 days period of pre-HK and 90 days period of HK. Rats were equally divided into two groups: hypokinetic rats (HKR) and vivarium control (VCR). The HKR group of rats was kept in small individual cages. Femur mineralization density, ash mineral content, calcium (Ca) and phosphate (P) content, and plasma Ca and P concentration were measured. In the HKR group body weight, femur mineralization, density, ash mineral content, Ca and P concentration decreased significantly (p < or = 0.01) while plasma Ca and P concentration increased significantly (p < or = 0.01) when compared with the VCR group. The measured parameters did not change significantly in the VCR group when compared with the baseline control values. It was concluded that prolonged HK induces a significant reduction in electrolyte concentration accompanied by decreased mineralization, density, and ash mineral content of the femur of rats.

Potassium supplements' effect on potassium balance in athletes during prolonged hypokinetic and ambulatory conditions.

Electrolyte supplements may be used to prevent changes in electrolyte balance during hypokinesia (diminished movement). The aim of this study was to measure the effect of potassium (K) supplements on K balance during prolonged hypokinesia (HK). Studies were done during 30 d of a pre-HK period and during 364 d of an HK period. Forty male athletes aged 25.1+/-4.4 yr were chosen as subjects. They were divided equally into four groups: unsupplemented ambulatory control subjects (UACS), unsupplemented hypokinetic subjects (UHKS), supplemented hypokinetic subjects (SHKS) and supplemented ambulatory control subjects (SACS). The SHKS and UHKS groups were kept under an average walking distance of 0.7 km/d. The SACS and SHKS groups were supplemented daily with 50.0 mg elemental potassium chloride (KCl) per kilogram body weight. The K balance, fecal K excretion, urinary K, sodium (Na), and chloride (Cl) excretion, plasma K, Na, and Cl concentration, plasma renin activity (PRA) and plasma aldosterone (PA) concentration, anthropometric characteristics and peak oxygen uptake were measured. Negative K balance, fecal K excretion, urinary K, Na, and Cl excretion, plasma K, Na, and Cl concentration, and PRA and PA concentration increased significantly (p < or = 0.01), whereas body weight and peak oxygen uptake decreased significantly in the SHKS and UHKS groups when compared with SACS and UACS groups. However, the measured parameters changed much faster and much more in SHKS group than UHKS group. By contrast, K balance, fecal, urinary, and plasma K, plasma hormones, body weight, and peak oxygen uptake did not change significantly in the SACS and UACS groups when compared with the baseline control values. It was concluded that prolonged HK induces a significant negative K balance associated with increased plasma K concentration and urinary and fecal K excretion. However, negative K balance appeared much faster and was much greater in the SHKS group than UHKS group. Thus, K supplementation was not effective in preventing negative K balance during prolonged HK.

Calcium metabolism in bone and teeth of rats during exposure to restriction of motor activity and to swimming exercise.

The effects of motor activity restriction for 90 days (hypokinesia, HK) and swimming training (T) on calcium metabolism in rat bones and teeth were evaluated. Male Wistar rats were distributed in four groups: untrained vivarium control rats (UVCR), untrained hypokinetic rats (UHKR), trained hypokinetic rats (THKR) and trained vivarium control rats (TVCR). Hypokinesia was obtained keeping the animals for 90 days in small individual cages which restricted their movements in all directions without hindering food and water intakes. Rats of THKR and TVCR were forced to swim for 15 to 90 minutes everyday. On the 1st, 7th, 15th day of a prehypokinetic period and on the 5th, 10th, 20th, 40th, 60th and 90th day of the hypokinetic period, six rats of each group were decapitated. Radioactive calcium was injected to the animals 70 days before autopsy. Calcium and phosphorus in serum, bones (molars, incisors, upper and lower jaws, parietal, scapular, clavicle, pelvic and tibial bones) and in the respective ash residues were measured. Body and bone weights, and radioactive calcium were also determined. Under prolonged exposure to HK (THKR and UHKR groups), bone weights and bone and ash Ca and P concentrations decreased, whereas serum Ca and P and 45Ca resorption increased, in comparison to the respective values in the UVCR and TVCR groups. Swimming exercise apparently did not modify calcium metabolism in the hypokinetic or control rats.

Magnesium supplements' effect on magnesium balance in athletes during prolonged restriction of muscular activity.

Electrolyte supplements may be used to prevent negative electrolyte balance during hypokinesia (HK) (decreased number of kilometres per day). The aim of this study was to evaluate the effect of daily intakes of magnesium (Mg) supplements on Mg balance during prolonged HK. Studies were done during a 30-day period of pre-HK and during a 364-day period of HK. Forty male athletes aged 22-26 years were chosen as subjects. They were equally divided into four groups: unsupplemented ambulatory control (UACS), unsupplemented hypokinetic subjects (UHKS), supplemented hypokinetic subjects (SHKS) and supplemented ambulatory control subjects (SACS). The SHKS and UHKS groups were maintained under an average running distance of 1.7 km/day, while the SACS and UACS groups experienced no changes in their professional training and routine daily activities. The SHKS and SACS groups took daily 23 mg Mg as Mg lactate per kilogram body weight. Mg balance, urinary and faecal Mg excretion and serum Mg concentration, anthropometric characteristics and peak oxygen uptake were measured. Negative Mg balance, faecal and urinary Mg excretion and serum Mg concentration increased significantly (p