Effects of Black Widow Spider Venom on the Frog Neuromuscular Junction: Effects on the Fine Structure of the Frog Neuromuscular Junction

Nature ◽  
1970 ◽  
Vol 225 (5234) ◽  
pp. 703-705 ◽  
Author(s):  
ALLEN W. CLARK ◽  
ALEXANDER MAURO ◽  
HERBERT E. LONGENECKER ◽  
WILLIAM P. HURLBUT
Keyword(s):  
Fine Structure ◽  
Neuromuscular Junction ◽  
Spider Venom ◽  
Frog Neuromuscular Junction ◽  
Black Widow ◽  
Black Widow Spider ◽  
Black Widow Spider Venom ◽  
Widow Spider

scholarly journals CHANGES IN THE FINE STRUCTURE OF THE NEUROMUSCULAR JUNCTION OF THE FROG CAUSED BY BLACK WIDOW SPIDER VENOM

1972 ◽  
Vol 52 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Allen W. Clark ◽  
William P. Hurlbut ◽  
Alexander Mauro
Keyword(s):  
Neuromuscular Junction ◽  
Nerve Terminal ◽  
Synaptic Vesicles ◽  
Spider Venom ◽  
Presynaptic Membrane ◽  
Black Widow ◽  
Black Widow Spider ◽  
End Plate ◽  
Black Widow Spider Venom ◽  
Widow Spider

Application of black widow spider venom to the neuromuscular junction of the frog causes an increase in the frequency of miniature end-plate potentials (min.e.p.p.) and a reduction in the number of synaptic vesicles in the nerve terminal. Shortly after the increase in min.e.p.p. frequency, the presynaptic membrane of the nerve terminal has either infolded or "lifted." Examination of these infoldings or lifts reveals synaptic vesicles in various stages of fusion with the presynaptic membrane. After the supply of synaptic vesicles has been exhausted, the presynaptic membrane returns to its original position directly opposite the end-plate membrane. The terminal contains all of its usual components with the exception of the synaptic vesicles. The only other alteration of the structures making up the neuromuscular junction occurs in the axon leading to the terminal. Instead of completely filling out its Schwann sheath, the axon has pulled away and its axoplasm appears to be denser than the control. The relation of these events to the vesicle hypothesis is discussed.

scholarly journals Effects of black widow spider venom and Ca2+ on quantal secretion at the frog neuromuscular junction.

1986 ◽  
Vol 88 (1) ◽  
pp. 59-81 ◽  
Author(s):  
R Fesce ◽  
J R Segal ◽  
B Ceccarelli ◽  
W P Hurlbut
Keyword(s):  
Power Spectrum ◽  
Neuromuscular Junctions ◽  
Mean Amplitude ◽  
Spider Venom ◽  
Fluctuation Analysis ◽  
Frog Neuromuscular Junction ◽  
Black Widow ◽  
Black Widow Spider ◽  
Black Widow Spider Venom ◽  
Widow Spider

A modification of the classical procedure of fluctuation analysis is used to measure the waveform, w(t), mean amplitude, (h), and mean rate of occurrence, (r), of miniature endplate potentials (MEPPs) at frog cutaneous pectoris neuromuscular junctions treated with black widow spider venom (BWSV). MEPP parameters are determined from the power spectrum of the fluctuating potential and the second (variance), third (skew), and fourth semi-invariants (cumulants) of high-pass-filtered records of the potential. The method gives valid results even when the mean potential undergoes slow changes unrelated to MEPPs and when the MEPP rate is not stationary; it detects changes in the distribution of MEPP amplitudes and corrects for the nonlinear summation of MEPPs. The effects of Ca2+ on BWSV-induced secretion are studied in detail. When Ca2+ is absent, the power spectrum of the fluctuations is shaped like the spectrum of w(t) and secretion is quasi-stationary; (r) rises smoothly to peak values of approximately 1,500/s and then quickly subsides to levels near 10/s. Many relatively small and some "giant" MEPPs occur at the ends of the experiments, and the distribution of MEPP amplitudes broadens. When the effects of this broadening are corrected for, we find that approximately 0.7 X 10(6) MEPPs occurred during the 30 min of intense secretion. Since BWSV depletes nerve terminals of their quanta of transmitter and their synaptic vesicles, this figure is an upper limit for the quantal store in a resting terminal. When Ca2+ is present, the noise spectrum deviates from the spectrum of w(t) and secretion is nonstationary; (r) rises to similar peak values but is sustained at levels near 400/s for up to an hour and at least 1.5 X 10(6) quanta are secreted within this period. Thus, the quantal store must have turned over at least twice under this condition. Data previously obtained at junctions treated with La3+ are corrected for nonlinear summation and for the distribution of MEPP amplitudes. The two corrections roughly compensate each other, and the corrected results confirm the previous conclusion that the number of quanta secreted from La3+-treated terminals during 1 h is not strongly dependent upon the extracellular concentration of Ca2+; approximately 2 X 10(6) quanta are released even when Ca2+ is absent.

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