Focal, extracellular recording of slow miniature junctional potentials at the mouse neuromuscular junction

Vautrin, Jean; Kriebel, Mahlon E.

doi:10.1002/jnr.490310313

Cited by 9 publications

(3 citation statements)

References 23 publications

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“…While Katz's studies used muscle cells that were 30–50 micrometers in diameter, the muscle cells studied by Kriebel were only 6–10 micrometers in diameter. These findings were subsequently confirmed by others (Vautrin and Mambrini, 1981; Muniak et al, 1982; Wiegand et al, 1984; Erxleben and Kriebel 1988a, 1988b; Vautrin and Kriebel, 1991, 1992). Kriebel named each of the subunit signals of mEPPs as a subminiature end‐plate potentials (sub‐mEPP).…”

Section: Vesicle Diameter and Volumesupporting

confidence: 61%

Secretion without membrane fusion: Porocytosis

Silver

Pappas

2005

The Anatomical Record Part B

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We have recently proposed a mechanism to describe secretion, a fundamental process in all cells. That hypothesis, called porocytosis, embodies all available data and encompasses both forms of secretion, i.e., vesicular and constitutive. The current accepted view of exocytotic secretion involves the physical fusion of vesicle and plasma membranes; however, that hypothesized mechanism does not fit all available physiological data. Energetics of apposed lipid bilayers do not favor unfacilitated fusion. We consider that calcium ions (e.g., 10(-4) to 10(-3) M calcium in microdomains when elevated for 1 ms or less), whose mobility is restricted in space and time, establish salt bridges among adjacent lipid molecules. This establishes transient pores that span both the vesicle and plasma membrane lipid bilayers; the diameter of this transient pore would be approximately 1 nm (the diameter of a single lipid molecule). The lifetime of the transient pore is completely dependent on the duration of sufficient calcium ion levels. This places the porocytosis hypothesis for secretion squarely in the realm of the physical and physical chemical interactions of calcium and phospholipids and places mass action as the driving force for release of secretory material. The porocytosis hypothesis that we propose satisfies all of the observations and provides a framework to integrate our combined knowledge of vesicular and constitutive secretion.

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Section: Vesicle Diameter and Volumesupporting

confidence: 61%

Secretion without membrane fusion: Porocytosis

Silver

Pappas

2005

The Anatomical Record Part B

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“…It was shown that during development, hyperosmotic shock, or poisoning of the presynaptic terminal, miniature endplate potentials can show the same variability as miniature signals at central synapses, with a predominance of small amplitudes and short rise times. 18,20 Normal and small‐amplitude miniature endplate currents were shown to originate from the same release sites 33 and the release process to reversibly switch dynamically between the two types of mEPSPs. 21,20 One explanation for this phenomenon could be a change in the number and level of synchronization between TDs.…”

Section: Discussionmentioning

confidence: 99%

Miniature EPSPs and Sensory Encoding in the Primary Afferents of the Vestibular Lagena of the Toadfish, Opsanus tau

Locke

Vautrin

Highstein

1999

Annals of the New York Academy of Sciences

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The synaptic activity transmitted from vestibular hair cells of the lagena to primary afferent neurons was recorded in vitro using sharp, intracellular microelectrodes. At rest, the activity was composed of miniature excitatory postsynaptic potentials (mEPSPs) at frequencies from 5 to 20/s and action potentials (APs) at frequencies betwen 0 and 10/s. mEPSPs recorded from a single fiber displayed a large variability. For mEPSPs not triggering APs, amplitudes exhibited an average coefficient of variance (CV) of 0.323 and rise times an average CV of 0.516. APs were only triggered by mEPSPs with larger amplitudes (estimated 4-6 mV) and/or steeper maximum rate of rise (10.9 mV/ms, +/- 3.7 SD, n=4 experiments) compared to (3.50 mV/ms, +/-0.07 SD, n=6 experiments) for nontriggering mEPSPs. The smallest mEPSPs showed a fast rise time (0.99 ms between 10% and 90% of peak amplitude) and limited variability across fibers (CV:0.18) confirming that they were not attenuated signals, but rather represented single-transmitter discharges (TDs). The mEPSP amplitude and rise-time relationship suggests that many mEPSPs represented several, rather than a single pulse of secretion of TDs. According to the estimated overall TD frequency, the coincidence of TDs contributing to the same mEPSP were not statistically independent, indicating a positive interaction between TDs that is reminiscent of the way subminiature signals group to form miniature signals at the neuromuscular junction. Depending on the duration and intensity of efferent stimulation, a complete block of AP initiation occurred either immediately or after a delay of a few seconds. Efferent stimulation did not significantly change AP threshold level, but abruptly decreased mEPSP frequency to a near-complete block that followed the block of APs. Maximum mEPSP rate of rise decreased during, and recovered progressively after, efferent stimulation. After termination of efferent stimulation, mEPSP amplitude did not recover instantly and for a few seconds the amplitude distribution of synaptic events showed fewer large-amplitude events than during the control period. This confirms that mEPSP amplitude and rate of rise properties, which are critical for triggering afferent APs, are modified by efferent activity. The depression of afferent AP firing during efferent stimulation corresponded to a decrease in mEPSP frequency and, to a lesser extent, a decrease in mEPSP amplitude and rate of rise, suggesting, a decrease in the level of interaction among TDs contibuting to a mEPSP.

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“…Long rise time events induced by acute treatments are not due to remote transmitter action for the following reasons: (1) long rise times may be recorded with focal extracellular electrodes (Cooke and Quastel, 1973;Augustine and Levitan, 1983;Vautrin and Kriebel, 1992); (2) plitude and rise time relationship of signals generated at remote sites would be negatively correlated, whereas the data showed a positive correlation (Fig. 2D; Erxleben and Kriebel, 1986b;Vautrin and Kriebel, 1991a); and (3) many signals with long rise times had breaks (Vautrin and Kriebel, 1992). Spontaneous events are known to clump (Cohen et al, 1973;Kriebel and Stolper, 1975;Vautrin and Kriebel, 1991).…”

Section: Analyses Of Mepcsmentioning

confidence: 99%

Further evidence for the dynamic formation of transmitter quanta at the neuromuscular junction

Vautrin

Kriebel

Holsapple

1992

J of Neuroscience Research

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Fatt and Katz (Nature 166:597-598, 1950; J Physiol 117:109-128, 1952) attributed miniature endplate potentials (MEPPs) to the action of a standard quantity of transmitter, the quantum (Del Castillo and Katz, J Physiol 124:560-573, 1954). Quantal packets of transmitter were proposed to be preformed (Del Castillo and Katz, In CNRS Paris (Ed): "Microphysiologie comparée des éléments excitables" 67:245-258, 1957) and stored in large numbers in the motor nerve terminal. Statistical analyses of intervals between MEPPs and numbers of quanta composing small endplate potentials indicated that quantal release was a random process and that release sites functioned independently of each other. With the discovery of synaptic vesicles it was proposed that each contained one quantum of transmitter. The quantal-vesicular hypothesis (Del Castillo and Katz, as cited above) fails, however, to explain amplitude distributions of MEPPs that are skewed and/or that show multiple peaks (Kriebel et al., Brain Res Review 15:167-178, 1990). The drop formation process (Shaw, "The Dripping Faucet as a Model Chaotic System," Santa Cruz, CA: Aerial Press, Inc., 1984) was shown to generate amplitude classes of drops that were similar to classes of MEPPs which suggested that rapid changes in quantal size and ratios of skew- to bell-MEPPs could be explained with a simple dynamic process which determines quantal size at the moment of release (Kriebel et al., as cited above, 1990). Further similarities between miniature endplate currents (MEPCs) and the formation of drops are reported here. We found that rapid changes in MEPC amplitudes and time courses, which accompany an increase in frequency, mimic changes in drop sizes that accompany increases in flow rate. MEPC intervals have a minimum and their distributions are comparable to those of drop intervals. During an increased rate of transmitter release, MEPP amplitudes and intervals were positively correlated. The results suggest that spontaneously released transmitter "packets" are formed at the moment of release and that transmitter supply to the process that forms packets is continuous.

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Focal, extracellular recording of slow miniature junctional potentials at the mouse neuromuscular junction

Cited by 9 publications

References 23 publications

Secretion without membrane fusion: Porocytosis

Secretion without membrane fusion: Porocytosis

Miniature EPSPs and Sensory Encoding in the Primary Afferents of the Vestibular Lagena of the Toadfish, Opsanus tau

Further evidence for the dynamic formation of transmitter quanta at the neuromuscular junction

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