scholarly journals Voltage clamp of bull-frog cardiac pace-maker cells: a quantitative analysis of potassium currents.

1985 ◽  
Vol 368 (1) ◽  
pp. 265-292 ◽  
Author(s):  
W R Giles ◽  
E F Shibata
Keyword(s):  
Quantitative Analysis ◽  
Voltage Clamp ◽  
Potassium Currents ◽  
Cardiac Pace ◽  
Pace Maker

Effects of Hyposmolar Solutions on Membrane Currents of Hippocampal Interneurons and Mossy Cells In Vitro

1998 ◽  
Vol 79 (2) ◽  
pp. 1108-1112 ◽  
Author(s):  
Scott C. Baraban ◽  
Philip A. Schwartzkroin
Keyword(s):  
Voltage Clamp ◽  
Hippocampal Slices ◽  
Cell Voltage ◽  
Potassium Currents ◽  
Membrane Currents ◽  
Excitatory Postsynaptic Currents ◽  
Whole Cell ◽  
Mossy Cells ◽  
Postsynaptic Currents

Baraban, Scott C. and Philip A. Schwartzkroin. Effects of hyposmolar solutions on membrane currents of hippocampal interneurons and mossy cells in vitro. J. Neurophysiol. 79: 1108–1112, 1998. Whole cell voltage-clamp recordings in rat hippocampal slices were used to investigate the effect of changes in extracellular osmolarity on voltage-activated potassium currents. Currents were evoked from oriens/alveus (O/A) interneurons, hilar interneurons, and mossy cells. Hyposmolar external solutions produced a significant potentiation of K+ current recorded from O/A and hilar interneurons, but not from mossy cells. Hyposmolar solutions also dramatically potentiated the spontaneous excitatory postsynaptic currents recorded from mossy cells. These results suggest that hippocampal excitability can be modulated by the complex actions exerted by changes in extracellular osmolarity.

Evidence for a direct effect of somatostatin on cardiac pace-maker cells of guinea-pig

1985 ◽  
Vol 10 ◽  
pp. S49
Author(s):  
Marco Di Gennaro ◽  
Giovanni Ghirlanda ◽  
Luigi Uccioli ◽  
Guido Bianchini ◽  
AldoV. Greco ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Direct Effect ◽  
Cardiac Pace ◽  
Pace Maker

Properties of persistent sodium conductance and calcium conductance of layer V neurons from cat sensorimotor cortex in vitro

1985 ◽  
Vol 53 (1) ◽  
pp. 153-170 ◽  
Author(s):  
C. E. Stafstrom ◽  
P. C. Schwindt ◽  
M. C. Chubb ◽  
W. E. Crill
Keyword(s):  
Voltage Clamp ◽  
Sensorimotor Cortex ◽  
Potassium Currents ◽  
Spike Threshold ◽  
Sodium Conductance ◽  
Blocking Agents ◽  
Calcium Conductance ◽  
Layer V ◽  
Persistent Sodium Conductance

Properties of the persistent sodium conductance and the calcium conductance of layer V neurons from cat sensorimotor cortex were examined in an in vitro slice preparation by use of a single microelectrode, somatic voltage clamp, current clamp, intra- and extracellular application of blocking agents, and extracellular ion substitution. The persistent sodium current (INaP) attained its steady level within 2-4 ms of a step change in voltage at every potential where it could be examined directly [to about 40 mV positive to resting potential (RP)]. Because of its fast onset INaP can be activated during a single excitatory postsynaptic potential (EPSP) and can influence the subsequent voltage time course and cell excitability. Application of a depolarizing holding potential greater than or equal to 20 mV positive to RP could inactivate spikes, thus allowing examination of INaP at voltages positive to spike threshold. At every potential where INaP was visible, it was mixed with a slow outward current. After depressing potassium currents with blocking agents, INaP could be observed during depolarizations to about 40 mV positive to RP where it is normally hidden by the larger outward currents. Indirect evidence suggests that INaP is present and large during prolonged depolarizations greater than 50 mV positive to RP. INaP was blocked by intracellular injection of the lidocaine derivative QX-314, as well as by extracellular tetrodotoxin (TTX). INaP was much more sensitive to QX-314 than was the height and rate of rise of the spike. This observation and the results in paragraph 3 above are best explained by separate INaP and spike sodium channels. After blockade of INaP and sodium spikes, Ca2+ spikes could be evoked only if potassium currents were first depressed. The Ca2+-dependent nature of the regenerative potentials was indicated by their disappearance when Co2+ or Mn2+ was substituted for Ca2+ in the perfusate and by the appearance of greatly enhanced potentials of similar form when Ba2+ was substituted for Ca2+. Ba2+ substitution greatly enhanced evoked and spontaneous synaptic potentials. Prolonged-plateau action potentials could be evoked in the presence of TTX and Ba2+. Ca2+ spike threshold was 30-40 mV positive to RP, which is significantly more positive than sodium spike threshold. Results of voltage clamp in the normal perfusate and in the presence of Ca2+-blockers or Ba2+ indicated that little or no Ca2+ conductance is activated in the voltage range 25 mV positive to RP where INaP is the dominant ionic current.(ABSTRACT TRUNCATED AT 400 WORDS)

Sign in / Sign up

Export Citation Format

Share Document