scholarly journals Ionic Basis for Membrane Potential Resonance in Neurons of the Inferior Olive

Cell Reports ◽  
2016 ◽  
Vol 16 (4) ◽  
pp. 994-1004 ◽  
Author(s):  
Yoshiko Matsumoto-Makidono ◽  
Hisako Nakayama ◽  
Miwako Yamasaki ◽  
Taisuke Miyazaki ◽  
Kazuto Kobayashi ◽  
...  

1984 ◽  
Vol 108 (1) ◽  
pp. 305-314
Author(s):  
B. L. BREZDEN ◽  
D. R. GARDNER

The mean resting potential in the heart ventricle muscle cells of the freshwater snail Lymnaea stagnalis was found to be −61.2±3.5 (˙˙) mV (ranging from −56mV to −68mV). The average intracellular potassium concentration was estimated to be 51.5±14.6(˙˙) m (ranging from 27.8 m to 77.3 m). The membrane of the heart ventricle muscle cells appears to be permeable to both potassium and chloride, as changes in the extracellular concentration of either of these ions resulted in a change in the membrane potential. A ten-fold change in the extracellular potassium concentration was associated with a 50.4±3.8(˙˙) mV slope when the potassium concentration was above about 6 m. Deviations from the straight-line relation predicted for a potassium electrode could be accounted for by introducing a term for sodium permeability. The ionic basis of the membrane potential in these cells can be described by a modified form of the Goldman-Hodgkin- Katz equation.



1988 ◽  
Vol 234 (1275) ◽  
pp. 199-218 ◽  

Neurons of the inferior olive of the rat were studied at different stages of their postnatal (PN) development by using the current clamp technique in slices maintained in vitro . Antidromic and synaptic activation of inferior olivary neurons could be achieved in preparations as young as PN day 2. Neurons at this age already exhibited a variety of ionic conductances which included fast sodium-dependent spikes, high-threshold and low-threshold calcium spikes, potassium-dependent currents, Ca-dependent after-hyperpolarizing potentials (AHPS), and both instan­taneous and time-dependent inward rectification at hyperpolarized levels of membrane potential. The two types of Ca-dependent responses recorded in olivary neurons during the first postnatal week were graded with the magnitude of the depolarization imposed on the cells. Further­more, the high-threshold Ca spikes were only clearly observed during this early period when K conductances were depressed by the injection of caesium into the cells or by bath application of 4-aminopyridine. In contrast, the high-threshold Ca spikes could be obtained without sup­pression of K currents and were all-or-none in character in some neurons after PN day 8 and in all neurons after PN day 11. The observations suggest that the balance between K and Ca currents changes throughout maturation and is largely in favour of the K current until about the end of the first PN week. At all ages studied, the low-threshold Ca spikes were much less sensitive to the Ca channel blocker cadmium than were the high-threshold Ca spikes. Finally, spontaneous, regular oscillations of the membrane potential were observed for the first time at PN day 16 and were only commonly observed after PN day 19, suggesting a late develop­ment of electrotonic coupling between olivary neurons.



2005 ◽  
Vol 288 (6) ◽  
pp. H2931-H2939 ◽  
Author(s):  
L. Chilton ◽  
S. Ohya ◽  
D. Freed ◽  
E. George ◽  
V. Drobic ◽  
...  

Despite the important roles played by ventricular fibroblasts and myofibroblasts in the formation and maintenance of the extracellular matrix, neither the ionic basis for membrane potential nor the effect of modulating membrane potential on function has been analyzed in detail. In this study, whole cell patch-clamp experiments were done using ventricular fibroblasts and myofibroblasts. Time- and voltage-dependent outward K+ currents were recorded at depolarized potentials, and an inwardly rectifying K+ (Kir) current was recorded near the resting membrane potential (RMP) and at more hyperpolarized potentials. The apparent reversal potential of Kir currents shifted to more positive potentials as the external K+ concentration ([K+]o) was raised, and this Kir current was blocked by 100–300 μM Ba2+. RT-PCR measurements showed that mRNA for Kir2.1 was expressed. Accordingly, we conclude that Kir current is a primary determinant of RMP in both fibroblasts and myofibroblasts. Changes in [K+]o influenced fibroblast membrane potential as well as proliferation and contractile functions. Recordings made with a voltage-sensitive dye, DiBAC3(4), showed that 1.5 mM [K+]o resulted in a hyperpolarization, whereas 20 mM [K+]o produced a depolarization. Low [K+]o (1.5 mM) enhanced myofibroblast number relative to control (5.4 mM [K+]o). In contrast, 20 mM [K+]o resulted in a significant reduction in myofibroblast number. In separate assays, 20 mM [K+]o significantly enhanced contraction of collagen I gels seeded with myofibroblasts compared with control mechanical activity in 5.4 mM [K+]o. In combination, these results show that ventricular fibroblasts and myofibroblasts express a variety of K+ channel α-subunits and demonstrate that Kir current can modulate RMP and alter essential physiological functions.





1976 ◽  
Vol 104 (1) ◽  
pp. 71-92 ◽  
Author(s):  
Gary Kukes ◽  
Rafael Elul ◽  
Jean De Vellis


1984 ◽  
Vol 34 (6) ◽  
pp. 973-983 ◽  
Author(s):  
Toshihide SATO ◽  
Kumiko SUGIMOTO ◽  
Yukio OKADA ◽  
Takenori MIYAMOTO




2010 ◽  
Vol 588 (16) ◽  
pp. 3031-3043 ◽  
Author(s):  
Soonwook Choi ◽  
Eunah Yu ◽  
Daesoo Kim ◽  
Francisco J. Urbano ◽  
Vladimir Makarenko ◽  
...  


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