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  • 1
    Electronic Resource
    Electronic Resource
    Kinetic study on the effects of intracellular K++ and Na++ on Na++, K++, Cl+− cotransport of HeLa cells by Rb++ influx determination (1993)
    Springer
    The journal of membrane biology 132 (1993), S. 115-124 
    Details
    ISSN: 1432-1424
    Keywords: furosemide ; HeLa cells ; Na+ ; K+ ; Cl+− ; cotransport ; potassium ; rubidium influx ; sodium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The effects of intracellular K+ and Na+ (K+ c, Na+ c) on the Na+,K+,Cl+− cotransport pathway of HeLa cells were studied by measuring ouabain-insensitive, furosemide-sensitive Rb+ influx (JRb) at various intracellular concentrations of K+ and Na+ ([K+]c, [Na+]c). When [K+]c was increased and [Na+]c was decreased, keeping the sums of their concentrations almost constant, JRb as a function of the extracellular Rb+ or Na+ concentration ([Rb+]e, [Na+]e) was stimulated. However, the apparent K 0.5 for Rb+ e or Na+ e remained unchanged and the ratio of the apparent K +0.5 for K+ c and the apparent K i for Na+ c was larger than 1. When JRb was increased by hypertonicity by addition of 200 mM mannitol, the apparent maximum JRb increased without change in the apparent K 0.5 for Rb+ e. These results show that K+ c stimulates and Na+ c inhibits JRb, without change in the affinities of the pathway for Rb+ e and Na+ e. The affinity for K+ c is slightly lower than that for Na+ c. Hypertonicity enhances JRb without any change in the affinity for Rb+ e. We derived a kinetic equation for JRb with respect to K+ c and Na+ c and proposed a general and a special model of the pathway. The special model suggests that, in HeLa cells, JRb takes place when Rb+ e binds to the external K+ binding site of the pathway after the binding of K+ c to the internal regulatory site.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239001
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  • 2
    Electronic Resource
    Electronic Resource
    Kinetic mechanism of Na+, K+, Cl−-cotransport as studied by Rb+ influx into HeLa cells: Effects of extracellular monovalent ions (1986)
    Springer
    The journal of membrane biology 92 (1986), S. 135-150 
    Details
    ISSN: 1432-1424
    Keywords: chloride ; cotransport ; HeLa cells ; rubidium influx ; potassium ; sodium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Ouabain-insensitive, furosemide-sensitive Rb+ influx (J Rb) into HeLa cells was examined as functions of the extracellular Rb+, Na+ and Cl− concentrations. Rate equations and kinetic parameters, including the apparent maximumJ Rb, the apparent values ofK m for the three ions and the apparentK i for K+, were derived. Results suggested that one unit molecule of this transport system has one Na+, one K+ and two Cl− sites with different affinities, one of the Cl− sites related with binding of Na+, and the other with binding of K+(Rb+). A 1∶1 stoichiometry was demonstrated between ouabain-insensitive, furosemidesensitive influxes of22Na+ and Rb+, and a 1∶2 stoichiometry between those of Rb+ and36Cl−. The influx of either one of these ions was inhibited in the absence of any one of the other two ions. Monovalent anions such as nitrate, acetate, thiocyanate and lactate as substitutes for Cl− inhibited ouabain-insensitive Rb+ influx, whereas sulfamate and probably also gluconate did not inhibitJ Rb. From the present results, a general model and a specialized cotransport model were proposed: 1) In HeLa cells, one Na+ and one Cl− bind concurrently to their sites and then one K+ (Rb+) and another Cl− bind concurrently. 2) After completion of ion bindings Na+, K+(Rb−) and Cl− in a ratio of 1∶1∶2 show synchronous transmembrane movements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870703
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  • 3
    Electronic Resource
    Electronic Resource
    Changes in carotid blood flow and electrocardiogram in humans during and after walking on a treadmill (1993)
    Springer
    European journal of applied physiology 67 (1993), S. 486-491 
    Details
    ISSN: 1439-6327
    Keywords: Ultrasound ; Telemetry ; Exercise ; Blood flow velocity ; Heart rate ; Blood pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Blood flow velocity in the common carotid artery and the electrocardiogram were measured simultaneously by telemetry in seven male subjects during 20-min walking on a treadmill at an exercise intensity corresponding to a mean oxygen uptake of 26.0 (SD 2.9) ml · kg −1 · min −1. The mean cardiac cycle was shortened from 0.814 (SD 0.103) s to 0.452 (SD 0.054) s during this exercise. Of this shortening, 73% was due to shortening of the diastolic period and 27% to shortening of the systolic period. In the relatively small shortening of the mean systolic period [from 0.377 (SD 0.043) s to 0.268 (SD 0.029) s], the isovolumetric contraction time was shortened by 56%. During exercise, the heart rate (f c) increased by 79.4% [from 74.3 (SD 9.3) beats · min −1 to 133.3 (SD 14.8) beats · min −1], and the peak blood velocity (S1) in the common carotid artery increased by 56.1% [from 0.82 (SD 0.10) m · s−1 to 1.28 (SD 0.11) m · s−1]. After exercise, the S1 decreased rapidly to the resting level. The f c decreased more slowly, still being higher than the initial resting level 5 min after exercise. The diastolic velocity wave and the end-diastolic foot decreased during exercise. The blood flow rate in the carotid artery increased transiently by 13.5% at the beginning of exercise [from 5.62 (SD 0.63) ml · s−1 to 6.38 (SD 0.85) ml · s−1] and by 26.5% at the end of the exercise period [from 5.62 (SD 0.63) ml · s−1 to 7.11 (SD 1.34) ml · s−1]. The increase of blood flow in the carotid artery at the onset of exercise may have been mainly related to cerebral activation, and partly to an increase of blood flow to the skin of the head. The physiological significance for cerebral function of the increase of blood flow in the artery after the end of exercise is unknown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241643
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  • 4
    Electronic Resource
    Electronic Resource
    Blood flow velocity in the common carotid artery in humans during graded exercise on a treadmill (1995)
    Springer
    European journal of applied physiology 70 (1995), S. 234-239 
    Details
    ISSN: 1439-6327
    Keywords: Dynamic exercise ; Cerebral blood flow ; Flow resistance ; Resistance index ; Pulsatility index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cerebral blood volume flow and flow velocity have been reported to increase during dynamic exercise, but whether the two increase in parallel and whether both increases occur as functions of exercise intensity remain unsettled. In this study, blood flow velocity in the common carotid artery was measured using the Doppler ultrasound method in eight healthy male students during graded treadmill exercise. The exercise consisted of stepwise progressive increases and decreases in exercise intensity. The peak intensity corresponded to approximately 85% of maximal oxygen consumption. During this exercise, the heart rate (f c), mean blood pressure (BP) in the brachial artery and mean blood flow velocity (νcc) in the common carotid artery increased as functions of exercise intensity. At the peak exercise intensity, (f c), BP and νcc increased by 134.5%, 20.5% and 51.8% over the control levels before exercise (P 〈 0.01), respectively. The resistance index (RI) and pulsatility index (PI) were determined from the velocity profile and were expected to reflect the distal cerebral blood flow resistance. The RI and PI increased during the graded exercise, but tended to decrease at the highest levels of exercise intensity. As νcc increased with increases in exercise intensity it would be expected that cerebral blood flow would also increase at these higher intensities. It is also suggested that blood flow velocity in the cerebral artery does not proportionately reflect the cerebral blood flow during dynamic exercise, since the cerebral blood flow resistance changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238569
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  • 5
    Electronic Resource
    Electronic Resource
    Rb+ influx in response to changes in energy generation: Effect of the regulation of the ATP content of HELa cells (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 119 (1984), S. 273-282 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effect of changes in energy metabolism on Rb+ influx was studied in HeLa cells. Irrespective of whether ATP production was controlled by varying the activity of glycolysis or of oxidative metabolism on addition of certain combinations of glucose, carbonylcyanide m-chlorophenylhydrazone, monoiodoacetic acid, and quercetin, Rb+ influx changed as a linear function of the ATP content, which varied in a wide range up to the normal level (15-20 nmol/mg protein or 3-4 mM). The difference between results obtained by these procedures was not significant. As the intracellular Na+ content varied at different ATP contents, the Na+ content was adjusted to similar levels by chilling the cells with varying ATP contents. However, a linear relation was still observed. A similar dependence was also obtained for cytoplasmic ATP, which would be more closely connected with the Na, K-pump than total ATP. The ratio of ouabain-sensitive Rb+ influx to the corresponding part of lactate production was nearly 2 in the presence of 2 mM glucose. From these results it is concluded that (1) active Rb+ influx, which is chiefly maintained by energy generated through glycolysis, can also be supported by oxidative metabolism; (2) Rb+ influx is regulated linearly as a function of the cellular ATP content up to the control level; but does not increase if ATP is raised still further; and (3) 2 Rb+ ions move concomitantly at the expense of one ATP molecule.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041190305
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  • 6
    Electronic Resource
    Electronic Resource
    Stimulating effects of insulin and low-density lipoprotein on cell growth and macromolecular syntheses of HeLa cells cultured in K+-depleted medium (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 144 (1990), S. 254-261 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The influence of the intracellular K+ concentration on the effects of growth factors (insulin, EGF, hydrocortisone, and transferrin) and LDL on growth of HeLa cells was investigated. Upon replacenient of K+ in a chemically defined medium (K+-CDM) by Rb+ (Rb+-CDM), about 80% of the intracellular K+ was replaced by Rb+ within 24 h, but showed no further change in the next 24 h, irrespective of addition of dialyzed calf serum (5%) or growth factors to the medium. In Rb+-CDM, cell growth and DNA synthesis were greatly suppressed, although cell viability was not significantly altered for 72 h. The suppression of cell growth was partially restored by addition of serum, insulin (5 μg/ml), or LDL (2.5 mg/ml) to Rb+ -CDM. A combination of serum and insulin or insulin and LDL stimulated cell growth to approximately the level in K+-CDM without any addition, but a combination of serum and LDL did not have more effect than that of serum alone. Unexpectedly, other factors were ineffective in stimulating growth in Rb+-CDM. In Rb+-CDM, the effect of insulin was lost in 24-48 h, whereas that of LDL persisted for at least 96 h. Insulin and LDL also enhanced growth in K+-CDM. After cessation of cell growth in Rb+-CDM for 24 h, addition of insulin and/or LDL markedly restored cell growth and DNA synthesis. Therefore, insulin and LDL may stimulate certain mechanisms required for cell growth that can operate in K+-deficient conditions.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041440211
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  • 7
    Electronic Resource
    Electronic Resource
    Arrest of cell cycle progression of HeLa cells in the early G1 phase in K+-depleted conditions and its recovery upon addition of insulin and LDL (1993)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 53 (1993), S. 13-20 
    Details
    ISSN: 0730-2312
    Keywords: K+-depleted cells ; insulin ; LDL ; HeLa cells ; cell cycle ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Cell cycle progression of synchronized HeLa cells was studied by measuring labeling of the nuclei with [3H]thymidine. The progression was arrested in a chemically defined medium in which K+ was replaced by Rb+ (Rb-CDM) but was restored upon addition of insulin and/or low density lipoprotein (LDL). Cells started DNA synthesis 12 hr after addition of insulin and/or LDL, regardless of the time of arrest, suggesting their arrest early in the G1 phase. After incubation of cells in Rb-CDM containing insulin or LDL singly for 3, 6, or 9 hr, replacement of the medium by that without an addition resulted in marked delay in entry of cells into the S phase, but in its replacement by medium containing both agents, the delay was insignificant. Synthesis of bulk protein, estimated as increase in the cell volume, was not strongly inhibited. From these results we conclude that cell cycle progression of HeLa cells in K--depleted CDM is arrested early in the G1 phase and that the arrest is due to lack of some protein(s) required for entry into the S phase that is synthesized in the early G1 phase.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240530103
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  • 8
    Electronic Resource
    Electronic Resource
    Phenazine methosulfate stimulation of ouabain-sensitive Rb+ uptake by HeLa cells: Effects of respiratory inhibitors, anaerobiosis, and ascorbate (1985)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 28 (1985), S. 273-280 
    Details
    ISSN: 0730-2312
    Keywords: rubidium transport ; ouabain ; phenazine methosulfate ; anaerobiosis ; respiratory inhibitors ; ascorbate ; HeLa cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Phenazine methosulfate (PMS) stimulates ouabain-sensitive Rb+ uptake by HeLa cells. This stimulation cannot be attributed to the effect of the dye on the intracellular Na+ or ATP content. Respiratory inhibitors, such as 5 mM NaCN and 5 mM rotenone, and anaerobic conditions enhance the stimulation of Rb+ uptake by PMS. Cellular respiration is stimulated, but lactate production is reduced in the presence of PMS, irrespective of the presence of respiratory inhibitors. Cellular NADH is oxidized markedly on addition of PMS plus inhibitors, but it is not affected by addition of the inhibitors only. In the presence of a high concentration of PMS, PMS-stimulated ouabain-sensitive Rb+ uptake is inhibited by addition of ascorbate. From these results it is concluded that Na/K-pump activity is closely related to the cellular redox state.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240280405
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