Botulinum toxin and amphetamines ___________________.
 |
 |
increase the release of acetylcholine and norepinephrine from the presynaptic membrane, respectively; |
 |
act at axoaxonic synapses; |
 |
stimulate presynaptic facilitative heteroreceptors; |
 |
stimulate calcium ion influx; |
 |
all of the alternatives above are correct; |