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  • 1
    Electronic Resource
    Electronic Resource
    Calorimetric and spectroscopic studies of lipid thermotropic phase behavior in liver inner mitochondrial membranes from a mammalian hibernator (1988)
    s.l. : American Chemical Society
    Biochemistry 27 (1988), S. 4632-4638 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00413a008
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  • 2
    Electronic Resource
    Electronic Resource
    Adrenergic responses and the Root effect in erythrocytes of freshwater fish (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 38 (1991), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effects of adrenergic-stimulation upon the oxygen-binding capacity of fish erythrocytes have been investigated. The oxygen capacity of rainbow trout, Oncorhynchus mykiss (Walbaum), erythrocytes was lowered by 44% on extracellular acidification (the so-called ‘Root effect’). Addition of isoproterenol at 20° Ccaused an acid shift of the curve relating oxygen capacity to pH0 by approximately 0.2 pH units, a value which was similar to the change in intracellular pH caused by adrenergic stimulation (Cossins & Kilbey Journal of Experimental Biology, 148, 303–312, 1990). Moreover, when plotted as a function of pHi, the curves for control and adrenalinstimulated erythrocytes were superimposable suggesting that the adrenergic shift in the Root curve was a result of the change in pHi caused by activation of the adrenergic Na+/H+ exchanger.A similarly large adrenergic shift in the Root curve was observed for pike, Esox lucius L., erythrocytes, though not for erythrocytes of carp, Cyprinus carpio L., and tench, Tinea tinea (L.). The pH for the mid-point of the Root effect in pike erythrocytes was distinctly more acid than for trout, but in both cases corresponded closely with the optimal pH for the adrenergic Na+/H+ exchange mechanism. This suggests a link between the functional characteristics of the exchanger and the oxygen-binding properties of haemoglobin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1991.tb03131.x
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  • 3
    Electronic Resource
    Electronic Resource
    Thermal limits for behavioural function and resistance-adaptation of goldfish,Carassius auratus L. (1979)
    Springer
    Journal of comparative physiology 129 (1979), S. 241-246 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Goldfish were trained to perform a conditioned avoidance response in a shuttle tank at acclimation temperatures between 10 °C and 35 °C. A high level of success (85–100%) was maintained over a relatively wide range of test temperatures, although outside this range the response was rapidly and reversibly blocked. The upper and lower thermal limits for the avoidance response were determined in goldfish acclimated to temperatures between 10 °C and 35 °C. The absolute thermal limits for the avoidance response in goldfish were approximately 3 °C to 42 °C, but the range for individuals was considerably more restricted. Increased acclimation temperature resulted in higher upper and lower thermal limits and thus constitutes a reasonable resistance adaptation. Over the lower range of acclimation temperatures the upper thermal limit showed greater mobility, whereas over the upper range of acclimation temperatures the lower thermal limits showed greater mobility. Goldfish acclimated to 5 °C and 38.5 °C exhibited very reduced % success at their respective acclimation temperatures even though they showed high % success when the same individuals were previously acclimated to less stressful temperatures. These extreme acclimation temperatures probably represent the absolute limits for chronic exposure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00657660
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  • 4
    Electronic Resource
    Electronic Resource
    The effects of oxygenation upon the Cldependent K flux pathway in equine red cells (1996)
    Springer
    Pflügers Archiv 432 (1996), S. 270-277 
    Details
    ISSN: 1432-2013
    Keywords: Key words KCl cotransport ; Oxygen ; Kinase ; Phosphatase ; Equine red cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of oxygen tension (PO2) upon the K influx pathways of equine red cells have been studied using 86Rb+ as congener for K. Equilibration of cells in 100% nitrogen led to a low and Clindependent K flux. Change to an atmosphere of 100% air led to a rapid sixfold increase in K flux. The oxygen-activated flux was entirely Cl dependent and was maintained for up to 3 h. Oxygenation-evoked activation was dependent upon PO2 over the physiological range with little effect up to 70% saturation of haemoglobin with oxygen but significant effects between 70 and 100%. K flux at low PO2 was unaffected by acidification to pH 7 or by hypotonic cell swelling. By contrast, at high PO2 both manipulations caused a substantial increase in Cldependent K flux. N-Ethylmaleimide (NEM; 1 mM) caused a progressive activation of KCl cotransport in cells held under nitrogen. The protein phosphatase inhibitor, calyculin A (100 nM), applied during NEM-evoked activation caused a “clamping” of K influx at that level. This “clamped” activity was unaffected by subsequent oxygenation. We conclude that oxygenation exerts a primary control over cotransport activity and that acidification and cell swelling are secondary modulators. It appears that oxygenationevoked activation of the Cldependent K flux involves a serine/threonine phosphorylation event. Regulating the PO2 of the solution before and during experiments is important in controlling the activity of the KCl cotransporter and cell volume.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050133
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  • 5
    Electronic Resource
    Electronic Resource
    Protein tyrosine phosphorylation and the regulation of KCl cotransport in trout erythrocytes (1996)
    Springer
    Pflügers Archiv 432 (1996), S. 727-734 
    Details
    ISSN: 1432-2013
    Keywords: Key words Erythrocyte ; Vanadate ; Genistein ; Staurosporine ; Calyculin A
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Electroneutral salt transporters are activated and deactivated by changes to the phosphorylation status either of the transporter itself or of other, as yet unidentified, regulatory proteins. We have studied the effects of an inhibitor of protein tyrosine kinase (PTK), genistein, upon KCl cotransport in trout erythrocytes. We show that Cl-dependent K fluxes activated by physiological stimuli, i.e. oxygenation and β-adrenergic agonists, are rapidly and completely blocked by genistein, whilst the inactive analogue of genistein, daidzein, had no effect. By contrast, the protein tyrosine phosphatase (PTP) inhibitor, vanadate (V), caused a slow but strong activation of an inactive cotransporter. This vanadate (V) activated flux was inhibited by genistein as well as by the serine/threonine phosphatase (PSP) inhibitor, calyculin A. However, genistein had no effect upon the activation of the cotransporter by the protein (serine/threonine) kinase (PSK) inhibitor, staurosporine, or by N-ethylmaleimide, which also appears to act by inhibiting a PSK. These results are consistent with a sequential scheme of at least two tyrosine phosphorylation events which lie upstream to the serine/threonine phosphorylation sites in the signal transduction pathway leading from stimulus to transporter activation. The regulation of the activity of KCl cotransporter appears to involve a complex series of phosphorylation reactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050191
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  • 6
    Electronic Resource
    Electronic Resource
    Resistance adaptation of the freshwater crayfish and thermal inactivation of membrane-bound enzymes (1976)
    Springer
    Journal of comparative physiology 111 (1976), S. 15-24 
    Details
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Heat death and resistance adaptation of freshwater crayfish are thought to be properties of its muscle membranes. The inactivation at high temperatures of a membrane-bound enzyme, the Ca++-stimulated ATPase of crayfish abdominal muscle sarcoplasmic reticulum, and the effect of thermal acclimation of crayfish upon the inactivation kinetics have been investigated. In the absence of KCl, the Ca++-stimulated ATPase is irreversibly inactivated with pseudo-first order kinetics at temperatures that cause heat death in the whole animal. 0.1–10.0 mM KCl resulted in slower inactivation, while 100 mM KCl activated the enzyme to 120–180% of its original activity. Enzyme activation by KCl and heat involved a shift in the enzyme concentration/activity curve. Thermal acclimation of crayfish had no significant effect upon the kinetics or Arrhenius activation energy for enzyme inactivation (100.6±10.5 and 92.3±14.6 kcal/mole for preparations from 4°C and 25°C acclimated crayfish). Ca++-stimulated ATPase isolated from heat dead crayfish exhibited normal in vitro activity due presumably to the high intracellular K+ concentration. Nevertheless, the close correspondence between heat death temperatures and inactivation temperatures for several membrane-bound enzymes of muscle is thought to reflect some perturbation of muscle structure that occurs during heat death.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00691107
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    Paper (German National Licenses)
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