-
[show abstract]
[hide abstract]
ABSTRACT: Measuring calcium (Ca) absorption, Ca balance and Ca level in serum,feces and urine during HK (hypokinesia) with and without Ca loading, the aim of this study was to disclose if prolonged HK could reduce Ca deposition more with or without Ca load contributing to greater Ca imbalance. Studies were conducted during 30-days pre-HK and 364-days HK. Forty male normal volunteers 23.7+/-6.0 years of age were chosen as subjects. They were divided into four groups: unloaded active control subjects (UACS), unloaded hypokinetic subjects (UHKS), loaded active control subjects (LACS), loaded hypokinetic subjects (LHKS). All hypokinetic subjects were walking average distances of 0.5+/-0.2 km day(-1), and active control subjects were running average distances of 6.6+/-1.2 km day(-1). LACS and LHKS were loaded with 1.3 mmol calcium lactate/kg body wt. Before Ca load, fecal Ca loss, urinary Ca and phosphate (P) losses, Ca imbalance, serum ionized calcium (CaI), P and total Ca (Ca(t)) levels increased significantly. (P < 0.05) with time, and serum intact parathyroid hormone (iPTH), 1.25 dihydroxyvitamin D (1.25(OH)2D3) levels and Ca absorption, decreased significantly (P < 0.05) with time in LHKS and UHKS compared with their pre-HK values and their respective active controls (LACS and UACS). After Ca load, however, Ca absorption, serum iPTH and 1.25 (OH)2D3 levels decreased significantly (P < 0.05) more with time, while fecal Ca loss, urinary Ca and P excretion and Ca imbalance increased significantly (P < 0.05) more with time in LHKS than UHKS. Conversely, before and after Ca load, fecal Ca excretion, urinary P and Ca loss, serum CaI, P, Ca, iPTH and 1.25 (OH)2D3 levels, Ca absorption and Ca balance did not change in LACS and UACS compared with their pre-HK values. The greater Ca losses with than without Ca load have shown that the more Ca is consumed the more Ca is eliminated during HK and Ca imbalance. The significant increase of Ca loss with Ca imbalance demonstrated reduced Ca deposition. Dissociation between Ca loss and Ca imbalance demonstrated reduced Ca deposition as the mechanism of Ca imbalance development during HK.
International Urology and Nephrology 01/2004; 36(3):293-302. · 1.47 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Bed rest (BR) induces significant urinary and blood electrolyte changes, but little is known about the effect of fluid and salt supplements (FSS) on catabolism, hydration and electrolytes. The aim was to measure the effect of FSS on catabolism, body hydration and electrolytes during BR. Studies were done during 7 days of a pre-bed rest period and during 30 days of a rigorous bed rest period. Thirty male athletes aged, 24.6 +/- 7.6 years were chosen as subjects. They were divided into three groups: unsupplemented ambulatory control subjects (UACS), unsupplemented bed rested subjects (UBRS) and supplemented bed rested subjects (SBRS). The UBRS and SBRS groups were kept under a rigorous bed rest regime for 30 days. The SBRS daily took 30 ml water per kg body weight and 0.1 sodium chloride per kg bodyweight. Plasma sodium (Na), potassium (K), calcium (Ca) and magnesium (Mg) levels, urinary Na, K, Ca and Mg excretion, plasma osmolality, plasma protein level, whole blood hemoglobin (Hb) and hematocrit (Hct) level increased significantly (p < or = 0.05), while plasma volume (PV), body weight, body fat, peak oxygen uptake, food and fluid intake decreased significantly (p < or = 0.05) in the UBRS group when compared with the SBRS and UACS groups. In contrast, plasma and urinary electrolytes, osmolality, protein level, whole blood Hct and Hb level decreased significantly (p < or = 0.05), while PV, fluid intake, body weight and peak oxygen uptake increased significantly (p < or = 0.05) in the SBRS group when compared with the UBRS group. The measured parameters did not change significantly in the UACS group when compared with their baseline control values. The data indicate that FSS stabilizes electrolytes and body hydration during BR, while BR alone induces significant changes in electrolytes and body hydration. We conclude that FSS may be used to prevent catabolism and normalize body hydration status and electrolyte values during BR.
Acta Astronautica 07/2002; 50(12):765-74. · 0.61 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Rigorous bed rest (RBR) induces significant biochemical and circulatory changes. However, little is known about acute rigorous bed rest (ARBR). Measuring biochemical and circulatory variables during ARBR and RBR the aim of this study was to establish the significance of ARBR effect. Studies were done during 3 days of a pre-bed rest (BR) period and during 7 days of ARBR and RBR period. Thirty normal male individuals aged, 24.1 +/- 6.3 years were chosen as subjects. They were divided equally into three groups: 10 subjects placed under active control conditions served as unrestricted ambulatory control subjects (UACS), 10 subjects submitted to an acute rigorous bed rest served as acute rigorous bed rested subjects (ARBRS) and 10 subjects submitted to a rigorous bed rest served as rigorous bed rested subjects (RBRS). The UACS were maintained under an average running distance of 9.7 km day-1. For the ARBR effect simulation, ARBRS were submitted abruptly to BR for 7 days. They did not have any prior knowledge of the exact date and time when they would be asked to confine to RBR. For the RBR effect simulation, RBRS were subjected to BR for 7 days on a predetermined date and time known to them right away from the start of the study. Plasma renin activity (PRA), plasma cortisol (PC), plasma aldosterone (PA), plasma and urinary sodium (Na) and potassium (K) levels, heart rate (HR), cardiac output (CO), and arterial blood pressure (ABP) increased significantly, and urinary aldosterone (UA), stroke volume (SV) and plasma volume (PV) decreased significantly (p<0.05) in ARBRS and RBRS as compared with their pre-BR values and the values in UACS. Electrolyte, hormonal and hemodynamic responses were significantly (p<0.05) greater and occurred significantly faster (p<0.05) during ARBR than RBR. Parameters change insignificantly (p>0.05) in UACS compared with pre-BR control values. It was concluded that, the more abruptly muscular activity is restricted in experimental subjects while they are very active, the greater hemodynamic and biochemical change there is and probably in individuals whose muscular activity is abruptly terminated after an accident or sudden illness.
Acta Astronautica 07/2002; 50(11):713-20. · 0.61 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Hypokinesia (diminished movement) induces significant magnesium (Mg) changes; however, little is known about Mg deposition and Mg depletion during HK. Measuring the Mg level in some tissues during HK and post-HK and Mg supplement, we aimed to establish Mg deposition and Mg depletion during prolonged HK. Studies were done on 408, 13-wk-old male Wistar rats (370-390 g) for a 15-d pre-HK period, a 98-d HK period, and a 15-d post-HK period. Rats were equally divided into four groups: unsupplemented vivarium control rats (UVCR), unsupplemented hypokinetic rats (UHKR), supplemented vivarium control rats (SVCR), and supplemented hypokinetic rats (SHKR). Both UHKR and SHKR were kept in small individual cages. The SVCR and SHKR took 53 mg Mg/d. During the HK period, plasma, urinary, and fecal Mg levels increased significantly (p < or = 0.05), whereas during the post-HK period Mg deposition, muscle and bone Mg content decreased significantly (p < or = 0.05) in UHKR and SHKR when compared with their pre-HK values and their respective vivarium controls (UVCR and SVCR). During the initial days of the post-HK period, plasma, urinary, and fecal Mg levels decreased significantly (p < or = 0.05), whereas during the post-HK period Mg deposition, muscle and bone Mg content remained significantly (p < or = 0.05) depressed in UHKR and SHKR when compared with UVCR and SVCR, respectively. However, during the HK period and post-HK period Mg deposition, bone, muscle, plasma, urinary, and fecal Mg levels changed significantly (p < or = 0.05) more in SHKR than UHKR. By contrast, during the HK period and post-HK period. Mg deposition, muscle, bone, plasma, urinary, and fecal Mg values change insignificantly (p > 0.05) in UVCR and SVCR when compared with their pre-HK values. It was concluded that reduced muscle, bone, plasma, urinary, and fecal Mg during post-HK and Mg supplement may demonstrate Mg depletion, whereas higher Mg loss during HK despite reduced muscle and bone Mg and Mg depletion might demonstrate Mg deposition incapacity during HK.
Biological Trace Element Research 06/2002; 86(3):203-16. · 1.92 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Body hydration decreases significantly during hypokinesia (HK) (diminished movement), but little is known about the effect of fluid and salt supplements (FSS) on body hydration during HK. The aim of this study was to measure the effect of FSS on body hydration during HK. Studies were done during 30 days pre HK period and 364 days HK period. Thirty male athletes aged 24.5 +/- 6.6 yr were chosen as subjects. They were equally divided into three groups: unsupplemented ambulatory control subjects (UACS), unsupplemented hypokinetic subjects (UHKS) and supplemented hypokinetic subjects (SHKS). Hypokinetic subjects were limited to an average walking distance of 0.7 km day-1. The SHKS group took daily 30 ml of water/kg body weight and 0.1 g of sodium chloride (NaCl)/kg body weight. Control subjects experienced no changes in their professional training and routine daily activities. Plasma volume (PV), urinary and plasma sodium (Na) and potassium (K), plasma osmolality, plasma protein, whole blood hemoglobin (Hb) and hematocrit (Hct), plasma renin activity (PRA) plasma aldosterone (PA) levels, physical characteristics, food and fluid intakes were measured. Plasma osmolality, plasma protein, urinary and plasma Na and K, whole blood Hct and Hb, PRA and PA levels decreased significantly (p < or = 0.01), while PV and body weight increased significantly (p < or = 0.01) in the SHKS group when compared with the UHKS group and did not change when compared with the UACS group. Plasma osmolality, plasma protein, urinary and plasma Na and K, PRA and PA, whole blood Hb and Hct levels increased significantly (p < or = 0.01), while PV body weight, food and fluid intakes decreased significantly (p < or = 0.01) in UHKS group when compared with the SHKS and UACS groups. The measured parameters did not change in the UACS group when compared with their baseline control values. It was shown that during HK body hydration decreased significantly, while during HK and FSS body hydration increased significantly. It was concluded that daily intake of FSS prevents the decrease of PV and blunts the increase of activity of the PRA and PA during prolonged HK.
Acta Astronautica 06/2002; 50(10):641-51. · 0.61 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Hypokinesia (diminished movement) induces significant phosphate (P) excretion; however, little is known about the P deposition ability of the body during hypokinesia (HK). Using P loads, the aim of this study was to establish the deposition ability of the body to retain P during prolonged HK. Studies were done during a 30-d period of pre-HK and a 364-d period of HK. Forty male trained athletes aged 24.7 +/- 8.0 yr were chosen as subjects. They were equally divided into four groups: unloaded ambulatory control subjects (UACS), unloaded hypokinetic subjects (UHKS), loaded ambulatory control subjects (LACS), and loaded hypokinetic subjects (LHKS). All hypokinetic subjects were limited to an average walking distance of 0.7 km/d. Loading tests with 85.0 mg of calcium phosphate/kg body weight were performed on the LACS and LHKS. Fecal P loss, urinary calcium (Ca) and P loss, serum P, Ca, and the ionized calcium (CaI) levels increased significantly (p < or = 0.05) in the LHKS and UHKS groups when compared with the LACS and UACS groups, respectively. Serum intact parathyroid hormone (iPTH) and the 1,25-dihydroxyvitamin D3 [1,25-(OH)2 D3] levels decreased significantly (p < or = 0.05) in the LHKS and UHKS groups when compared with the LACS and UACS groups, respectively. After the P load, significant (p < or = 0.05) differences were observed between LHKS and UHKS groups regarding serum, urinary, and fecal P changes. Thus, the deposition capacity of P decreased significantly (p < or = 0.05) more in the LHKS group than in the UHKS group. The deposition of P, fecal P, urinary P and Ca, serum CaI, P, Ca, 1,25-(OH)2 D3, and iPTH changed insignificantly (p > 0.05) in control groups when compared with their baseline values. It was shown that after the P load, significant differences were observed between the loaded and unloaded hypokinetic subjects regarding serum, urinary, and fecal P values and P retention. The oral P load intensified P loss from the body. It was concluded that the higher the P intake increased the greater P loss and the lower P deposition and thus the less likely it is for the P load to benefit hypokinetic subjects.
Biological Trace Element Research 03/2002; 85(3):211-26. · 1.92 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Hypokinesia (diminished movement) induces muscle mineral depletion. However, the mechanism of muscle mineral depletion during hypokinesia (HK) remains unknown. Measuring electrolyte retention and electrolyte values in muscle, plasma, and urine during and after HK, the aim of this study was to discover if HK could depress mineral retention and lead to muscle mineral depletion. Studies were done on 204 13-wk-old male Wistar rats (370-390 g) during 10 d pre-HK period, 98 d HK period, and 15 d post-HK period. Rats were equally divided into two groups: vivarium control rats (VCR) and hypokinetic rats (HKR). All hypokinetic rats were kept for 98 d in small individual cages, which restricted their movements in all directions without hindering food and water intakes. All control rats were housed for 98 d in individual cages under vivarium control conditions. Both groups of rats were pair-fed. During the HK period skeletal muscle sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), and water content and electrolyte retention decreased significantly (p < 0.05), while urinary and plasma electrolyte levels increased significantly (p < 0.05) in HKR compared with their pre-HK values and their respective VCR. During the initial days of the post-HK period, mineral retention increased significantly (p < 0.05), plasma and urinary electrolyte level decreased significantly (p < 0.05), while muscle electrolyte and water content remained significantly (p < 0.05) depressed in HKR compared with VCR. Muscle mineral and water content, electrolyte retention, plasma, and urinary electrolyte values did not change in VCR compared with their pre-HK values. It was concluded that during HK decreased muscle mineral content may suggest muscle mineral depletion, while increased urinary electrolyte loss and muscle mineral depletion may demonstrate reduced mineral retention. Reduced electrolyte excretion and depressed muscle mineral content during post-HK may indicate skeletal muscle mineral depletion during HK. Dissociation between electrolyte retention and muscle mineral depletion may demonstrate the presence of decreased electrolyte retention as the mechanism of muscle electrolyte depletion during prolonged HK.
Biological Trace Element Research 02/2002; 90(1-3):155-73. · 1.92 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Hypokinesia (diminished movement) induces significant potassium (K) changes; however, little is known about K deposition and deficiency during hypokinesia (HK). Using K supplements during and after HK, the aim was to establish body K deposition and K deficiency during HK. Studies were done during the pre-HK period of 30 d, HK period of 364 d, and post-HK period of 30 d. Forty male trained athletes aged 24.9 +/- 8.0 y were chosen as subjects. They were equally divided into four 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 0.7 km/d. Control subjects ran an average distance of 11.6 km/d. The SHKS and SACS groups took 95.0 mg elemental K/kg body weight daily. Fecal K excretion, urinary sodium (Na) and K excretion, plasma K and Na levels, plasma renin activity (PRA), plasma aldosterone (PA), food and fluid intake, and physical characteristics were measured. During HK, fecal K loss, urinary K and Na loss, and plasma K, Na, PRA, and PA levels increased significantly (p < or = 0.05), whereas during the initial days of post-HK, the levels of the measured parameters decreased significantly (p < or = 0.05) in the SHKS and UHKS groups as compared with the SACS and UACS groups, respectively. During HK, body weight, body fat, peak oxygen uptake, food and fluid intake decreased significantly (p < or = 0.05), whereas during the initial days of post-HK period remained significantly (p < or = 0.05) depressed and fluid intake increased in SHKS and UHKS groups when compared with the SACS and UACS groups, respectively. However, during HK and post-HK plasma, urinary, and fecal K changed significantly (p < or = 0.05) more in the SHKS group than in the UHKS group. The deposition of K was significantly (p < or = 0.05) lower and K deficiency much higher in the SHKS group than in the UHKS group. Fecal K loss, urinary K and Na loss, plasma K, Na, PRA, and PA levels, body weight, body fat, peak oxygen uptake, and food and fluid intake did not change significantly in the SACS and UACS when compared with their baseline control values. It was shown that plasma K concentration and urinary and fecal K excretion increased during HK and decreased significantly (p < or = 0.05) during post-HK. Oral K supplements did not influence plasma or fecal and urinary K either during HK or post-HK. It was concluded that the low plasma K level and fecal and urinary K loss during post-HK may indicate the presence of K deficiency, and increased K in plasma, urine, and feces during HK and in the presence of K deficiency may suggest the body's inability to retain K during HK.
Biological Trace Element Research 01/2002; 85(1):1-22. · 1.92 Impact Factor
