healthy 25-year-old man participates in a study of muscle function. The electrophysiologic observations made on a muscle biopsy specimen are shown. Via iontophoresis, 1um acetylcholinen (Ach) was applied to the muscle surface. Extracellular Ca2+ concentration was decreased to prevent end-plate potentials from acting as a suprathreshold for muscle action potentials.
Normal muscle:
eep Amplitude meep Amplitude Response (in mV) to Ach
10 (in mV) 1 (in mV) 1 (1 uM)
[eep = end-plate potential; meep = miniature epp]
Based on these findings, which of the following electrophysiologic characteristics is expected in a muscle biopsy specimen from a patient with ACUTE BOTULISM?
eep Amplitude (in mV) meep Amplitude (inmV) Response (in mV) to Ach (1 um)
A) 1 0.5 0.5
B) 1 1 1
C) 2 0.2 0.2
D) 5 0.2 0.1
E) 15 1 1
whats Meep?
Miniature end plate potential : is the smallest possible depolarization that is induced in the muscle.
It is produced by a single vesicle containing ach which is released at the NM junction in the absence of action potential. Its like a random release…