Kinetics of the sodium pump in red cells of different temperature sensitivity.

Ellory, J. C.; Willis, John S.

doi:10.1085/jgp.79.6.1115

Cited by 31 publications

(23 citation statements)

References 24 publications

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“…extracellular K + or intracellular Na + and ATP). However, we consider this unlikely because substrate concentrations were at saturating levels at room temperature, and previous studies on the Na + /K + -ATPase have shown that the cold increases the apparent affinity for extracellular K + and intracellular Na + (Ellory and Willis, 1982), and for ATP (Marjanovic and Willis, 1992). Furthermore, both the ATPbinding pocket and cation-binding sites of the Antarctic and temperate orthologs are conserved.…”

Section: Based Onmentioning

confidence: 98%

Physiological adaptation of an Antarctic Na+/K+-ATPase to the cold

Galarza-Muñoz

Soto-Morales

Holmgren

et al. 2011

Journal of Experimental Biology

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SUMMARYBecause enzymatic activity is strongly suppressed by the cold, polar poikilotherms face significant adaptive challenges. For example, at 0°C the catalytic activity of a typical enzyme from a temperate organism is reduced by more than 90%. Enzymes embedded in the plasma membrane, such as the Na + /K + -ATPase, may be even more susceptible to the cold because of thermal effects on the lipid bilayer. Accordingly, adaptive changes in response to the cold may include adjustments to the enzyme or the surrounding lipid environment, or synergistic changes to both. To assess the contribution of the enzyme itself, we cloned orthologous Na + /K + -ATPase -subunits from an Antarctic (Pareledone sp.; -1.8°C) and a temperate octopus (Octopus bimaculatus; ~18°C), and compared their turnover rates and temperature sensitivities in a heterologous expression system. The primary sequences of the two pumps were found to be highly similar (97% identity), with most differences being conservative changes involving hydrophobic residues. The physiology of the pumps was studied using an electrophysiological approach in intact Xenopus oocytes. The voltage dependence of the pumps was equivalent. However, at room temperature the maximum turnover rate of the Antarctic pump was found to be 25% higher than that of the temperate pump. In addition, the Antarctic pump exhibited a lower temperature sensitivity, leading to significantly higher relative activity at lower temperatures. Orthologous Na + /K + pumps were then isolated from two tropical and two Arctic octopus. The temperature sensitivities of these pumps closely matched those of the temperate and Antarctic pumps, respectively. Thus, reduced thermal sensitivity appears to be a common mechanism driving cold adaptation in the Na + /K + -ATPase. Supplementary material available online at

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Section: Based Onmentioning

confidence: 98%

Physiological adaptation of an Antarctic Na+/K+-ATPase to the cold

Galarza-Muñoz

Soto-Morales

Holmgren

et al. 2011

Journal of Experimental Biology

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“…Failure at low temperature hinges on the loss of control of gradients Since the recognition of these main features 20 years ago, much effort has failed to yield a clearly useful kinetic clue, as to what aspect of the Na'-K' pump mechanism accounts for the difference in its activity between cold-sensitive and cold-tolerant mammalian cells. Ellory & Willis (1982) investigated the effect of cooling on the affinity of the pump for its monovalent cationic substrates (cytoplasmic Na' and external K+). While there were changes in affinities for the ligand cations with cooling, the effect was similar in cold-sensitive and cold-tolerant cells.…”

Section: Introductionmentioning

confidence: 99%

ATP dependence of Na(+)‐K+ pump of cold‐sensitive and cold‐tolerant mammalian red blood cells.

Marjanović

Willis

1992

The Journal of Physiology

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SUMMARY1. The ATP concentration of intact, cold-tolerant (ground squirrel) red cells and cold-sensitive (guinea-pig and human) red cells was monitored by use of the firefly tail, luciferin-luciferase assay. ATP kinetics of the pump in intact red blood cells was investigated by altering cell [ATP] by progressive depletion of ATP in the presence of 2-deoxy-D-glucose and then by measurement of ouabain-sensitive K+ influx at each level of [ATP] at various temperatures between 37 and 5 'C. Na+-K+-ATPase activity of broken membranes was also determined in parallel experiments using ouabain-sensitive release of 32p from [y-32P]ATP as a measure of activity.2. Without depletion, there is no immediate decrease in [ATP] of intact coldsensitive cells at low temperature (5 'C) at times when there are marked differences in the activities of the Na+-K+ pump of cold-tolerant and cold-sensitive cells.3. At 37 'C Na+-K+-ATPase of all three species exhibited two components of ATP dependence at 37 0C, one with high velocity, low affinity, the other with low velocity, high affinity. Affinities of both components rose with cooling. 4. A similar, two component pattern was observed in intact guinea-pig and human red cells at 37 'C, except that the segment corresponding to the high affinity component had an apparent Km (Michaelis-Menten constant) 3-to 4-fold higher than that of the broken membrane preparation.5. Cooling intact guinea-pig and human red cells decreased the apparent affinity of the high velocity, low affinity component for ATP, so that at 20 'C the value of Km approached or exceeded the levels of physiological ATP concentration. Below 20 'C only one component with values corresponding to that of the low velocity, high affinity component could be observed.6. In intact ground squirrel cells only the low affinity, high velocity component was apparent between 37 and 5 'C. Its affinity for ATP rose with cooling between 37 and 5 'C.

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“…Even at low temperatures (0-10°C), the pump has been shown to be slightly active (0.2% to 0.8% of activity measured at 37°C). 16 Furthermore, our observations indicate that orthodirectional fluxes in the presence of ouabain are slightly greater than those in its absence (compare Tables 1 and 2). The high intracellular sodium and extracellular potassium may stimulate the pump and this would facilitate movement of these ions in the "reverse" direction.…”

Section: Discussionmentioning

confidence: 54%

Temperature dependence and bidirectional cation fluxes in red blood cells from spontaneously hypertensive rats.

Harris¹,

Guthe²,

Veer³

et al. 1984

Hypertension

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SUMMARY The net passive influx of Na + and efflux of K + (orthodirection) through the red blood cell membranes from spontaneously hypertensive rats (SHR) were observed to be significantly higher (p < 0.05) than those of three strains of normotensive rats when the measurements were made at 4°C. Similar comparative studies, carried out at 37°C, in the absence or presence of ouabain, showed no difference in these fluxes through this membrane from SHR compared to those from Wistar-Kyoto (VVKY) rats, one of the normotensive strains. A study was undertaken to determine the temperature at which the greater cation fluxes in SHR red blood cells occurred. The net fluxes of Na + and K + decreased as the temperature was reduced from 37° to 15°C, but a paradoxical increase in the fluxes was observed as the temperature was decreased from 15° to 4°C. Only with this temperature shift (15°t o 4°C) was the increase in flux significantly greater in SHR than in VVKY cells. Subsequent studies were designed to determine whether the difference in the transport systems of red blood cells of SHR and VVKY could be observed in fluxes of these cations in either direction across the membrane. For "reverse direction" flux studies, red blood cells were loaded with Na + (to 130 mEq/liter cell water) and depleted of K + (to 30 mEq/liter cell water) by incubation with the ionophore monensin. The reverse passive efflux of Na + and influx of K + at 4°C of cells from SHR were significantly greater than those of VVKY. Thus, the abnormality of the red blood cell membrane in SHR behaves as if it were just an increase in the size or number of pores through which Na + and K + diffuse freely at low temperatures. (Hypertension 6: 42-48, 1984)

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Kinetics of the sodium pump in red cells of different temperature sensitivity.

Cited by 31 publications

References 24 publications

Physiological adaptation of an Antarctic Na+/K+-ATPase to the cold

Physiological adaptation of an Antarctic Na+/K+-ATPase to the cold

ATP dependence of Na(+)‐K+ pump of cold‐sensitive and cold‐tolerant mammalian red blood cells.

Temperature dependence and bidirectional cation fluxes in red blood cells from spontaneously hypertensive rats.

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