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Titolo:
INTRACELLULAR SODIUM HOMEOSTASIS IN RELATION TO THE EFFECTIVE FREE-ENERGY CHANGE OF ATP HYDROLYSIS - STUDIES OF CRAYFISH MUSCLE-FIBERS
Autore:
COMBS CA; ELLINGTON R;
Indirizzi:
FLORIDA STATE UNIV,DEPT BIOL SCI,B-157 TALLAHASSEE FL 32306 FLORIDA STATE UNIV,DEPT BIOL SCI TALLAHASSEE FL 32306 FLORIDA STATE UNIV,NATL HIGH MAGNET FIELD LAB TALLAHASSEE FL 32306
Titolo Testata:
Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology
fascicolo: 8, volume: 167, anno: 1997,
pagine: 563 - 569
SICI:
0174-1578(1997)167:8<563:ISHIRT>2.0.ZU;2-8
Fonte:
ISI
Lingua:
ENG
Soggetto:
NUCLEAR-MAGNETIC-RESONANCE; PERFUSED RAT-HEART; FILTERED NA-23 NMR; ISCHEMIC HEARTS; GLOBAL-ISCHEMIA; NA+/H+ EXCHANGE; CELLULAR-ENERGY; PH REGULATION; P-31 NMR; DEPENDENCE;
Keywords:
CELLULAR ENERGY STATE; INTRACELLULAR SODIUM; CRAYFISH; MUSCLE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
41
Recensione:
Indirizzi per estratti:
Citazione:
C.A. Combs e R. Ellington, "INTRACELLULAR SODIUM HOMEOSTASIS IN RELATION TO THE EFFECTIVE FREE-ENERGY CHANGE OF ATP HYDROLYSIS - STUDIES OF CRAYFISH MUSCLE-FIBERS", Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology, 167(8), 1997, pp. 563-569

Abstract

We investigated the impact of reductions in the effective free-energychange of ATP hydrolysis (dG/d xi(ATP)) on intracellular sodium homeostasis in bundles of fibers from the abdominal extensor muscle of the crayfish Procambarus clarkii. P-31 nuclear magnetic resonance (NMR) spectroscopy was used to monitor high-energy phosphate levels and intracellular pH while interleaved Na-23-NMR spectra were acquired to monitor changes in sodium. Previous work has shown that the bulk of intracellular Na+ is NMR visible (see Ivanics et al. 1994). The Na-23-NMR spectra were diffusion-weighted which effectively filtered out signal contributions from extracellular sodium. The efficacy of this procedure was validated using a relatively non-toxic chemical shift reagent which allowed resolution of extracellular and intracellular Na+ signals. Metabolic inhibition (cyanide/iodoacetate) produced pronounced reductionsin dG/d xi(ATP) coincident with dramatic increases in intracellular Na+ levels ([Na+](i)). However, the increases in [Na+](i) occurred at dG/d xi(ATP) values well above the threshold value of -46 kJ.mol(-1) required by the existing Na+ gradient and the membrane potential. These results suggest that the global dG/d xi(ATP) value may not reflect thedG/d xi(ATP) value in the vicinity of the pump. Alternatively, other factors, including low molecular modulators of Na+, K+-ATPase activity, may be important in this context.

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Documento generato il 07/04/20 alle ore 22:42:31