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  • 1995-1999  (3)
  • Carbohydrate feeding  (1)
  • Cell integrity  (1)
  • Isometric contraction  (1)
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Material
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  • 1995-1999  (3)
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Effects of calcium, magnesium, potassium and boron on sperm cells isolated from pollen of Zea mays L. (1995)
    Springer
    Sexual plant reproduction 8 (1995), S. 113-122 
    Details
    ISSN: 1432-2145
    Keywords: Zea mays ; Calcium ; Cell integrity ; Cell viability ; Sperm cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Our previous studies showed that Brewbaker and Kwack salts, which have been widely used in pollen germination and sperm isolation, are not appropriate for the maintenance of isolated maize (Zea mays L.) sperm cells. In the present study, we have characterized the effects of each BKS component salt on the integrity of isolated sperm cells using hemacytometry. At 0.01 and 0.1 mM, there were no differences in cell number between control and any salt-treated cells except a 22% decrease with 0.1 mM MgSO4 at 48 h. At the 1 mM level, cell number decreased with time in the presence of Ca(NO3)2 and MgSO4, with loss of integrity of most cells at 48 h, while KNO3 and H3BO3 had little or no effect. Further characterization of calcium-induced reduction in cell integrity using flow cytometry showed that depletion of possible residual free calcium by addition of EGTA to the suspension medium improved cell longevity and viability. Exposure of isolated sperm cells to 1 mM calcium had no effect on cell integrity and viability in 5 h; however, only 12% of cells remained intact at 24 h. The reduction in cell integrity was hastened when cells were pretreated with the calcium ionophore A23187 prior to exposure to 1 mM calcium, with a 54% reduction in cell number at 1 h and complete cell lysis at 24 h. However, depletion of cytosolic free calcium by pretreatment of cells with the calcium ionophore followed by resuspension in the presence of EGTA resulted in rapid reduction of cell integrity as well. These results collectively suggest that maize sperm cells are sensitive to exogenous free calcium; however, a certain level of cytosolic free calcium is necessary for maintenance of integrity. Mechanisms of calcium-induced reduction in cell integrity are discussed along with possible roles of the sensitivity of sperm cells to calcium in fertilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230898
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of carbohydrate-electrolyte drinks on marathon running performance (1995)
    Springer
    European journal of applied physiology 70 (1995), S. 154-160 
    Details
    ISSN: 1439-6327
    Keywords: Carbohydrate feeding ; Marathon running ; Glucose metabolism ; Hormonal responses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this study was to compare the effects of drinking two carbohydrate (CHO) electrolyte solutions and water on marathon running performance. Seven endurance-trained runners completed three 42.2-km treadmill time-trials which were randomly assigned and 4 weeks apart. On each occasion the subjects ingested 3 ml · Kg−1 body weight of either water (W), a 6.9% CHO solution (O) or a 5.5% CHO solution (L) immediately prior to the start of the run and 2 ml · kg−1 body weight every 5 km thereafter. The total volume of fluid ingested [mean (SEM)] was 1112 (42), 1116 (44) and 1100 (44) ml, respectively. Running times for W, O and L trials were 193.9 (5.0), 192.4 (3.3) and 190.0 (3.9) min, respectively. Performance time for the L trial was faster (P 〈 0.05) compared with that of the W trial. Running speed was maintained in the L trial, whereas it decreased after 10 km (P 〈 0.05) in the W and after 25 km (P 〈 0.05) in the O trial. Blood glucose and lactate, and hormonal responses to fluid ingestion were similar in all three trials. Higher plasma free fatty acid and glycerol concentrations were observed at the end of the W trial compared with those obtained after the O and L trials, respectively (P 〈 0.05). Plasma ammonia concentration was higher (P 〈 0.01) at the end of the L trial compared with the W trial. Plasma creatine kinase concentration was higher (P 〈 0.05) 24 h after the completion of the L trial than after the W trial. This study shows that the ingestion of a 5.5% CHO solution improves marathon running performance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00361543
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Anthropometric determination of thigh volumes and thigh forces following acute training of increasing intensity in adult men (1996)
    Springer
    European journal of applied physiology 72 (1996), S. 528-536 
    Details
    ISSN: 1439-6327
    Keywords: Ultrasonics ; Isometric contraction ; Lactates ; Rate of perceived exertion ; Age
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purpose of the present study was to investigate the influence of submaximal training of increasing intensity on the rate of fatigue and on the anthropometry of the quadriceps muscle. A group of 24 middle-aged male subjects trained three times a week for 12 weeks at incremental exercise intensities which elicited 66%–83% of the maximal heart rate reserve; 11 male subjects acted as controls. A purpose-built, isometric chair with an adjustable force transducer ensured a standard posture for each subject during a 20 s maximal voluntary contraction (MVC). The muscle plus bone mass of the thigh was calculated from a previously validated anthropometric method reinforced by measurements derived from water displacement and ultrasonics. Training-induced submaximal relationships were assessed by means of two ergometer tests of progressive intensity. Following training, the subjects' blood lactate concentrations had decreased from 5.5 (SD 1.7) to 3.9 (SD 1.4) mmol·1−1 (P 〈 0.01) at the final exercise intensities. They increased thigh volumes from 10.7 (SD 1.7) to 11.0 (SD 1.7) 1 (P 〈 0.05) and thigh forces in 47.5% (P 〈 0.05) of the measurements. Heart rates and rates of perceived exertion were reduced (P 〈 0.01) following training; for the controls, all the above parameters remained constant. These results would seem to indicate that a submaximal type of training could enable a group of middle-aged men to increase the isometric forces of the thigh muscles by almost 50% when completing a MVC test following training. This suggests that this is a more suitable, safer form of maintaining and increasing maximal thigh forces for this, and older, age groups than specific isometric training alone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00242286
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    Paper (German National Licenses)
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