On the membrane potential independent mechanism of the sodium pump-induced inhibition of spontaneous electrical activity of japanese land snail neurons

1984 ◽  
Vol 77 (3) ◽  
pp. 577-583 ◽  
Author(s):  
M Kojima ◽  
S.N Ayrapetyan ◽  
K Koketsu
Keyword(s):  
Membrane Potential ◽  
Electrical Activity ◽  
Sodium Pump ◽  
Land Snail ◽  
Snail Neurons ◽  
Spontaneous Electrical Activity ◽  
Independent Mechanism

Measurement of spontaneous neuronal membrane activity by time lapse confocal microscopy

1995 ◽  
Vol 53 ◽  
pp. 972-973
Author(s):  
R H. Selinfreund ◽  
A. H. Cornell-Bell
Keyword(s):  
Membrane Potential ◽  
Confocal Microscopy ◽  
Patch Clamp ◽  
Electrical Activity ◽  
Time Lapse ◽  
Neuronal Firing ◽  
Neuronal Membrane ◽  
Pituitary Cells ◽  
Patch Clamp Recording ◽  
Spontaneous Electrical Activity

Cellular electrophysiological properties are normally monitored by standard patch clamp techniques . The combination of membrane potential dyes with time-lapse laser confocal microscopy provides a more direct, least destructive rapid method for monitoring changes in neuronal electrical activity. Using membrane potential dyes we found that spontaneous action potential firing can be detected using time-lapse confocal microscopy. Initially, patch clamp recording techniques were used to verify spontaneous electrical activity in GH4\C1 pituitary cells. It was found that serum depleted cells had reduced spontaneous electrical activity. Brief exposure to the serum derived growth factor, IGF-1, reconstituted electrical activity. We have examined the possibility of developing a rapid fluorescent assay to measure neuronal activity using membrane potential dyes. This neuronal regeneration assay has been adapted to run on a confocal microscope. Quantitative fluorescence is then used to measure a compounds ability to regenerate neuronal firing.The membrane potential dye di-8-ANEPPS was selected for these experiments. Di-8- ANEPPS is internalized slowly, has a high signal to noise ratio (40:1), has a linear fluorescent response to change in voltage.

Electrical activity of the ventromedial nucleus of the hypothalamus

1959 ◽  
Vol 197 (4) ◽  
pp. 829-834 ◽  
Author(s):  
Dana C. Brooks
Keyword(s):  
Electrical Activity ◽  
Slow Waves ◽  
Ventromedial Nucleus ◽  
Spontaneous Electrical Activity ◽  
Pentobarbital Anesthesia

The spontaneous electrical activity of the ventromedial nucleus was studied in the cat under pentobarbital anesthesia and in the unanesthetized, unrestrained state. Under light pentobarbital anesthesia the activity of the nucleus is characterized by a predominant 9–15 cps, 50–100 µv component which is uniform from second to second. With small additional doses of anesthesia there is a selective depression of this activity; with recovery from light anesthesia this activity is gradually replaced by irregular, large, slow waves characteristic of sleep. When the unanesthetized animal is aroused 20–35 cps activity having an amplitude of 40 µv or more appears in the nucleus. While the pattern of activity during sleep resembles that seen elsewhere in the hypothalamus, the activity seen during barbiturate anesthesia and during arousal is confined to the nucleus and not seen in other parts of the diencephalon.

Optical approaches to ontogeny of electrical activity and related functional organization during early heart development

1991 ◽  
Vol 71 (1) ◽  
pp. 53-91 ◽  
Author(s):  
K. Kamino
Keyword(s):  
Electrical Activity ◽  
Heart Development ◽  
Functional Organization ◽  
Embryonic Heart ◽  
Optical Recording ◽  
Additional Advantage ◽  
Physiological Functions ◽  
Spontaneous Electrical Activity ◽  
Somite Stage ◽  
Voltage Sensitive Dyes

Direct intracellular measurement of electrical events in the early embryonic heart is impossible because the cells are too small and frail to be impaled with microelectrodes; it is also not possible to apply conventional electrophysiological techniques to the early embryonic heart. For these reasons, complete understanding of the ontogeny of electrical activity and related physiological functions of the heart during early development has been hampered. Optical signals from voltage-sensitive dyes have provided a new powerful tool for monitoring changes in transmembrane voltage in a wide variety of living preparations. With this technique it is possible to make optical recordings from the cells that are inaccessible to microelectrodes. An additional advantage of the optical method for recording membrane potential activity is that electrical activity can be monitored simultaneously from many sites in a preparation. Thus, applying a multiple-site optical recording method with a 100- or 144-element photodiode array and voltage-sensitive dyes, we have been able to monitor, for the first time, spontaneous electrical activity in prefused cardiac primordia in the early chick embryos at the six- and the early seven-somite stages of development. We were able to determine that the time of initiation of the contraction is the middle period of the nine-somite stage. In the rat embryonic heart, the onset of spontaneous electrical activity and contraction occurs at the three-somite stage. In this review, a new view of the ontogenetic sequence of spontaneous electrical activity and related physiological functions such as ionic properties, pacemaker function, conduction, and characteristics of excitation-contraction coupling in the early embryonic heart are discussed.

Long-term observations of spontaneous electrical activity of the uterine smooth muscle

1959 ◽  
Vol 196 (2) ◽  
pp. 343-350 ◽  
Author(s):  
C. Y. Kao
Keyword(s):  
Smooth Muscle ◽  
Electrical Activity ◽  
Action Potentials ◽  
Local Conditions ◽  
Pregnant Uterus ◽  
Implanted Electrodes ◽  
Spontaneous Electrical Activity ◽  
Myometrial Cells ◽  
Uterine Smooth Muscle

The spontaneous electrical activity of uterine smooth muscle was rather variable when acute observations were made. Therefore, a series of chronic experiments was performed with implanted electrodes to monitor a group of myometrial cells under different physiological conditions for periods up to eight weeks. The results showed that consistent behavior of myometrial cells could be observed provided similar hormonal status was maintained. Action potentials were rare or absent in myometrium of oophorectomized animals but were caused to appear by estrogen. In the pregnant uterus, action potentials increased both in amplitude and frequency of discharge as parturition approached, reached a peak at that time, and then declined in the postpartum days. The results indicated that in estrogen treatment and in parturition activities of myometrial cells were more synchronous. There was suggestive evidence that there were central impulses initiating activity in the pregnant uterus, and that the responses of the myometrium were affected by the local conditions.

Nucleotide action on spontaneous electrical activity of calcium deficient nerve

1967 ◽  
Vol 70 (3) ◽  
pp. 257-264 ◽  
Author(s):  
Albert S. Kuperman ◽  
Michiko Okamoto ◽  
Elaine Gallin
Keyword(s):  
Electrical Activity ◽  
Spontaneous Electrical Activity

Electrical activity of small intestinal smooth muscle and its temperature dependence

1975 ◽  
Vol 229 (5) ◽  
pp. 1268-1276 ◽  
Author(s):  
TY El-Sharkawy ◽  
EE Daniel
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Electrical Activity ◽  
Temperature Dependence ◽  
Intestinal Smooth Muscle ◽  
Plateau Phase ◽  
Control Activity ◽  
Electrical Control ◽  
Electrical Control Activity ◽  
Small Intestinal

Some important features of the intracellularly recorded electrical control activity of rabbit jejunal smooth muscle and its temperature dependence are reported in this study. This activity consisted of repetitive 18-mV depolarizations (control potentials (CP) or slow waves), which at 37degreesC lasted 2 s and had a frequency of 18/min and arose from a membrane potential of --55 mV. In some cells periods between CP's exhibited "diastolic" progressive depolarizations (intercontrol-potential depolarization), which may be the trigger of the CP in driving cells. While CP was usually monophasic, some cells persistently exhibited a notch early in the plateau phase. We suggest that CP consists of two components, an "initial depolarization" and a "secondary depolarization," which are usually fused together to give a monophasic potential. Cooling reduced CP frequency and prolonged its duration and caused more cells to show notching. While amplitude and rate of CP initial depolarization had low Q10's, duration and rates of onset and offset of the secondary depolarization had higher Q10's. Thus, the process responsible for secondary depolarization is more sensitive to temperature thant that underlying initial depolarization of the CP.

Catecholaminergic automatic activity in the rat pulmonary vein: electrophysiological differences between cardiac muscle in the left atrium and pulmonary vein

2009 ◽  
Vol 297 (1) ◽  
pp. H102-H108 ◽  
Author(s):  
Nicolas Doisne ◽  
Véronique Maupoil ◽  
Pierre Cosnay ◽  
Ian Findlay
Keyword(s):  
Membrane Potential ◽  
Electrical Activity ◽  
Cardiac Muscle ◽  
Left Atrium ◽  
Pulmonary Vein ◽  
Pulmonary Veins ◽  
Muscle Membrane ◽  
Resting Membrane Potential ◽  
Ectopic Activity ◽  
Automatic Activity

Ectopic activity in cardiac muscle within pulmonary veins (PVs) is associated with the onset and the maintenance of atrial fibrillation in humans. The mechanism underlying this ectopic activity is unknown. Here we investigate automatic activity generated by catecholaminergic stimulation in the rat PV. Intracellular microelectrodes were used to record electrical activity in isolated strips of rat PV and left atrium (LA). The resting cardiac muscle membrane potential was lower in PV [−70 ± 1 (SE) mV, n = 8] than in LA (−85 ± 1 mV, n = 8). No spontaneous activity was recorded in PV or LA under basal conditions. Norepinephrine (10−5 M) induced first a hyperpolarization (−8 ± 1 mV in PV, −3 ± 1 mV in LA, n = 8 for both) then a slowly developing depolarization (+21 ± 2 mV after 15 min in PV, +1 ± 2 mV in LA) of the resting membrane potential. Automatic activity occurred only in PV; it was triggered at approximately −50 mV, and it occurred as repetitive bursts of slow action potentials. The diastolic membrane potential increased during a burst and slowly depolarized between bursts. Automatic activity in the PV was blocked by either atenolol or prazosine, and it could be generated with a mixture of cirazoline and isoprenaline. In both tissues, cirazoline (10−6 M) induced a depolarization (+37 ± 2 mV in PV, n = 5; +5 ± 1 mV in LA, n = 5), and isoprenaline (10−7 M) evoked a hyperpolarization (−11 ± 3 mV in PV, n = 7; −3 ± 1 mV in LA, n = 6). The differences in membrane potential and reaction to adrenergic stimulation lead to automatic electrical activity occurring specifically in cardiac muscle in the PV.

Chronic electrical activity of cat intestine

1984 ◽  
Vol 246 (4) ◽  
pp. G335-G341 ◽  
Author(s):  
A. Bortoff ◽  
L. F. Sillin ◽  
A. Sterns
Keyword(s):  
Electrical Activity ◽  
Slow Waves ◽  
Intestinal Anastomoses ◽  
Bipolar Electrodes ◽  
Spontaneous Electrical Activity ◽  
Central Origin ◽  
Variable Duration

Spontaneous electrical activity was recorded with bipolar electrodes from the gastrointestinal tracts of unanesthetized fasted cats (upper and lower cut-off frequencies: 35 and 3 Hz). In addition to slow waves (SWs) and spike potentials (SPs), the following three patterns of activity were recorded that are not observed in vitro. 1) Intense bursts of SPs (migrating spike complexes, MSCs) migrate caudally at a velocity of approximately 1 mm/s. MSCs resemble migrating myoelectric complexes (MMCs) in their velocity and by their traversal of intestinal anastomoses. SWs are usually suppressed during and immediately after the MSC, and, on their return, propagate at a higher velocity than they do prior to the MSC. Unlike its effect on MMCs, motilin does not appear to elicit MSCs, a finding consistent with the fact that MSCs occur infrequently in the duodenum and not at all in the antrum. 2) Bursts of SPs are found in the absence of recorded SWs. The SP bursts are of variable duration and occur virtually simultaneously at several recording sites, or propagate at 1-2 cm/s in either direction along the jejunum. The more usual caudally propagating SPs occur when SWs reappear. 3) "Minute rhythms," periods of spiking SWs, occur simultaneously over long lengths of upper bowel, sometimes including antrum, at intervals of about 1-2 min. It is proposed that, despite their differences, the cat MSC may be the functional counterpart of the MMC, that cat SWs are not omnipresent, and that the minute rhythms described here are of central origin.

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