synaptic transmission lab

Question 1

Why do individual MEPP’s vary substantially in amplitude

Answer 1

Vesicles may have different amounts of neurotransmitters in them, and Ach is destroyed in the synapse by ACHE

Question 2

Are MEPPs present in elevated Mg/low Ca solution? How about EPPS?

Answer 2

MEPP’s will persist in elevated Mg/Low Ca b/c they are spontaneous and do not depend on high ca levels (evoked but not spontaneous release is affected by this solution. EPPs will also show up, but will appear as quantal steps that look more like MEPPS (they always show up after the stimulaion though)

Question 3

What happens when a muscle in high Mg/low Ca is stimulated at low or high frequency?

Answer 3

The muscle will be blocked at a low frequency/single stimulus b/c the low calcium prevents transmitter release. At high frequency, facilitation will occur and allow the muscle to contract

Question 4

How does curare effect muscle during single stimulus and high frequency? Why

Answer 4

the muscle preparation will not contract in response to either a single stimulus or high-frequency stimulation. Curare blocks ACH receptors on muscle surface. Facilitation can occur at first, followed by depression

Question 5

Are MEPPS/EPPS present in the curare solution

Answer 5

MEPP’s will not be detectable in the curare
solution because of the reduced sensitivity of the post-synaptic membrane produced by blockade of Ach receptors. EPPS will be detectable, but will be decreased by about 80%.

Question 6

What does neostigmine do and what is it used to treat

Answer 6

Blocks acetylcholinesterase- used in myasthenia gravis

Question 7

How does neostigmine overdose occur

Answer 7

it resembles Ach, so if too high of conc it can bind to the post synaptic receptors