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* NBME 15 Block 1 Q 15
 #731755  
  tchongsu - 05/01/13 14:19
 
  Does anybody have an explanation for this question?

15) A 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



 
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* Re:NBME 15 Block 1 Q 15
#2880890
  tchongsu - 05/01/13 14:21
 
  Sorry if unclear, format was altered.

But according to NBME, A is wrong.
 
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* Re:NBME 15 Block 1 Q 15
#2880921
  mzk - 05/01/13 16:18
 
  basically in acute botulism there is no change becoz ach is not released into the nerve terminal ...... so it will stay in a a static state ...... B is the correct answer coz there is no stimulation nor inhibition  
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