Molecule hyperpolarization

This initial system, though not optimized for this particular application in medicine, has since been superseded by more appropriate systems with other choices of the components [48]. Finally, possible applications for using selectively hyperpolarized fluorine-containing molecules as contrast agents for medical imaging techniques appear especially attractive however, this subject matter is discussed elsewhere [50]. 

Stimulation of active H+ extrusion from roots (Cesco, 1995 Pinton et al., 1997 Table 9.1) and transmembrane potential hyperpolarization (Slesak and Jurek, 1988) indicated the involvement of the PM H+-ATPase in the increased nutrient uptake generally observed in the presence of humic substances. Direct proof of an interaction between humic molecules and the PM H+-ATPase has been obtained by Vara-nini et al. (1993), who demonstrated that low-molecular-weight (<5kDa) humic molecules at concentrations compatible with those present in the rhizosphere can stimulate the phospho-hydrolytic activity of this enzyme in isolated PM vesicles (Table 9.1). Further proof of the action of humic molecules on PM FT-ATPase activity and on nutrient uptake mechanisms was obtained when studying the effect of these molecules on NO3 uptake. Transport of this nutrient is a substrate-inducible process and involves FT co-transport. At higher uptake rates, the levels and activity of root PM FT-ATPase increased (Santi et al., 1995). The short-term (4h) contact... 

Robinson RB, Siegelbaum SA (2003) Hyperpolarization-activated cation currents from molecules to physiological function. Annu Rev Physiol 65 453-80 Rogan MT, Staubli UV, LeDoux JE (1997) Fear conditioning induces associative long-term potentiation in the amygdala. Nature 390 604-7... 

Increasing the NMR Signal with Hyperpolarization. A very promising avenue for increasing sensitivity in NMR and MRI is to increase the signal from the molecules being detected. The low radio-frequency energy used for NMR means that... 

Robinson RB, Siegelbaum SA. Hyperpolarization-activated cation currents from molecules to physiological function. Anna Rev Physiol 2003 65 453-480. 

Stimulation of inhibitory neurons causes movement of ions that results in a hyperpolarization of the postsynaptic membrane. These inhibitory postsynaptic potentials (IPSP) are generated by the following (1) Stimulation of inhibitory neurons releases neurotransmitter molecules, such as Y-aminobutyric acid (GABA) or glycine, which bind to receptors on the postsynaptic cell membrane. This causes a transient increase in the permeability of specific ions, such as, potassium and chloride ions. (2) The influx of chloride (Cl ) and efflux of potassium (K+) cause a weak hyperpolarization or inhibitory post-... 

Metarhodopsin II is the excited form of rhodopsin that initiates the guanine nucleotide amplification cascade that causes nerve stimulation. The final event is a hyperpolarization of the outer section membrane of the rod or cone caused by the closure of sodium and calcium channels through the membrane - excitation of a single molecule of rhodopsin, the action of a single photon, causes a drop of 1 pA in the normal dark current across this membrane... 

Metarhodopsin 11 activates transducin, leading to an exchange of bound GDP for GTP several hundred molecules of transducin are activated by a single molecule of metarhodopsin 11 within a fraction of a second. Transducin-GTP binds to, and activates, GMP phosphodiesterase, lowering the intracellular concentration of cGMP. As cGMP falls, a cation channel in the membrane closes, thus interrupting the steady inward current of sodium and calcium ions. This leads to hyperpolarization of the membrane and reduced secretion of neurotransmitter (Baylor, 1996). 

---