Sodium gradient

Hypertonic sahne is actively excluded from an intact BBB and also acts to draw water into the intravascular space by the creation of a sodium gradient. Various concentrations have been evaluated, with continuous sodium chloride infusions ranging from 3% to 9%, and bolus infusions up to 23.4% administered over 20 minutes in a 30 mL solution. When a continuous infusion is used, the serum sodium is typically titrated to the 155-160 range. Sodium levels above this range raise the concern for seizures and other toxic side effects. Hypertonic saline may hold an advantage over mannitol, as it has been found in animal models to decrease edema in both... 

Matsuura, H., Shattock, M.J. and Hearse, D.J. (1991). Calcium overload induced by oxidant stress is dependent on an intact transarcolemmal sodium gradient. J. Mol. Cell. Cardiol. 23, S7. 

We have described the initial functions of calcium outside cells in Section 5.5. Here we draw attention again to its later function in association with manganese in 02 production, described in the previous section (see Figure 5.9). We have also left out of this chapter any reference to vanadium as the first functional use of it known to us is in nitrogenase which was probably not required in the earliest organisms (see Section 6.5). The sodium gradient was utilised to cotransport nutrients into cells and this function remains a major use of the Na+ ion in later organisms. 

Rejection of Na+, Cr and Ca2+ (and Mn2+) to control cytoplasmic ionic solutions, with uptake of K+, and other elements by pumps or exchangers, mechanical catalysts the sodium gradient was used to assist nutrient uptake, the gradient itself being driven by the bioenergetic proton gradient... 

This antiporter (NCX) uses the sodium gradient to move calcium against its concentration gradient from the cytoplasm to the extracellular space. Extracellular concentrations of these ions are much less labile than intracellular concentrations under physiologic conditions. The sodium-calcium exchanger s ability to carry out this transport is thus strongly dependent on the intracellular concentrations of both ions, especially sodium. 

Stabilizes the threshold against hyperexcitability caused by excessive stimulation or environmental changes capable of reducing membrane sodium gradient, possibly by promoting sodium efflux from neurons... 

Digitoxin causes inhibition of the Na+/K+ ATPase, this reduces the sodium gradient and leads to increased intracellular calcium. This causes the adverse effects, including vomiting, diarrhea, visual disturbances, hypotension, and ventricular tachycardia, leading to fibrillation. 

The sodium gradient in the methanogen Methanococcus voltae is exploited in the transport of isoleucine as a positively charged complex,74 where concentration gradients over 100 can be achieved. It is noteworthy that the methanogens represent one of the few cases where a growth requirement for Na+ can be shown.75,76... 

Spironolactone reportedly has hypotensive activity when given to hypertensive patients, by blocking the effect of aldosterone on arteriolar smooth muscle by altering the extracellular-intracellular sodium gradient. 

Duffey, M.E., Tumheim, K., Frizzell, R.A., Schultz, S.G. (1978). Intracellular chloride activities in rabbit gallbladder Direct evidence for the role of the sodium-gradient in energizing uphill chloride transport. J. Membr. Biol. 42, 229-245. 

The biotin-dependent decarboxylases of anerobic microorganisms are transmembrane proteins. In addition to their roles in the metabolism of ox-aloacetate, methylmalonyl CoA, and glutaconyl CoA, they serve as energy transducers. They transport 2 mol of sodium out of the cell for each mole of substrate decarboxylated. The resultant sodium gradient is then used for active transport of substrates by sodium cotranspoit systems, or maybe used to drive ATP synthesis in a similar manner to the proton gradient in mammalian mitochondria (Buckel, 2001). 

Although plasma membrane monoamine transporters are responsible for the reuptake of neurotransmitters from the synapse, vesicular monoamine transporters (VMAT) sequester monoamines into synaptic vesicles in preparation for fusion with the plasma membrane and release into the synapse (Schuldiner et ah, 1995). Vesicular uptake is coupled to a proton gradient across the vesicle membrane rather than the sodium gradient used with the plasma membrane transporters (Schuldiner et ah, 1995). These vesicular transporters are not neurotransmitter-speciflc rather, they transport the monoamines nonselectively (Johnson, Jr., 1988 Henry et ah, 1998). 

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