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ATP-sensitive potassium channels in freshly dissociated adult rat striatal neurons: activation by metabolic inhibitors and the dopaminergic receptor agonist quinpirole (2000)

Sun, Xiao-Dong ; Lee, Esther W. ; Wong, Erik H. ; [et al.]

Springer

Pflügers Archiv 440 (2000), S. 530-547

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ISSN: 1432-2013

Keywords: Striatal neurons ATP-sensitive K+ channels

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Abstract. The characteristics of adenosine 5′-triphosphate (ATP)-sensitive K+ channels in acutely isolated striatal neurons from adult rats were examined. Neurons had a resting membrane potential of –53.9±1.2 mV (n=66), with evoked or spontaneous action potentials firing at 10±0.7 Hz, and large inwards and outwards whole-cell currents. In cell-attached patches with a high [K+] in the pipette, a voltage-independent, ATP-insensitive 16.5±1.5 pS channel was observed in 375 out of 452 cells. Bath application of Na+-azide (0.5–2 mM) to 108 neurons revealed another 145.7±3.5 pS (LKATP) channel in 65 neurons; this channel was blocked by tolbutamide. The LKATP channel exhibited a high open probability (P o, 0.8±0.05) at 0 mV pipette potential. Varying the pipette [K+] shifted the reversal potential of LKATP, showing the channel's K+ selectivity. Cytoplasmic ATP (ATPi) reversibly inhibited LKATP, with an inhibitory constant (K i) of 0.12 mM. LKATP was sensitive to intracellular Ca2+ but insensitive to iberiotoxin. In 25% of cell-attached patches, the presence of quinpirole in the pipette opened a third type of channel (90.6±1.7 pS, termed D2KATP). Sulpiride, a dopamine D2-receptor antagonist, inhibited D2KATP. ATPi reversibly inhibited D2KATP, with a K i of 0.212 mM. The Na+-azide- or quinpirole-induced current caused a tolbutamide-sensitive membrane hyperpolarization and a marked reduction in action potential frequency. We propose that ATP-sensitive K+ channels play a metabolism-dependent role in striatal neurons.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004240000322

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Study of ion solvation and ion association in polymer gel electrolyte with polyethylene oxide-co-polypropylene oxide as a plasticizer (1996)

Sun, Xiao Guang ; Li, Bin ; Lin, Yun Qing ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Polymer International 41 (1996), S. 301-305

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ISSN: 0959-8103

Keywords: gel electrolyte ; polytriethylene glycol dimethacrylate ; ion solvation ; ion association ; molal conductance ; Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics

Notes: Using a molal conductance method, ion solvation and ion association in polytriethylene glycol dimethacrylate (PTREGD)-LiClO4 gel electrolytes with amorphous ethylene oxide-co-propylene oxide (EO-co-PO, M̄n = 1750) as the plasticizer were investigated. It was found that the fraction of solute existing as single ions (αi) and ion pairs (αp) decreases, while that of triple ions (αt) increases linearly with increasing salt concentration. The dependence of these fractions on molecular weight of plasticizer was also examined. It was shown that αi and αt increase and αp decreases with increasing molecular weight. The result of temperature dependence of these fractions was very interesting: when the temperature is lower than 55°C, αi increases while αp and αt decrease with increasing temperature; however, when the temperature is higher than 55°C, the reverse is true.

Additional Material: 4 Ill.