Lab report
Acknowledgements
In order to obtain the data for this experiment # collected the data from The Virtual Twitch software as
labpartners (table 1).
Abstract:
Estimating and evaluating nerve signals in vitro of a rat hemidiaphragm injected by Tetradoxin, Tubocurarine,
4-Aminopyridine and Neostigmine in The Virtual Twitch software.
Introduction:
Many factors play a part in producing a drug response, however there are some basic responses of the human
body when exposed to drugs. Endogenous signaling is chemical signaling from within our own body that is
called “full agonists” in pharmacology. A drug can be a partial agonist, which only produces partial response
compared to the full agonist, which produces a maximal effect. The potency and efficacy of a drug is also
important when considering the characteristics of a drug. Exogenous and endogenous chemical signaling can
interact with each other and affect the affinity of the binding site of the receptor which in turn affects the overall
response. Competitive antagonist- and irreversible antagonist-drugs, can decrease the number of available
receptors and decrease the maximal response respectively. A graded dose response curve illustrates the intricate
interactions of a biological response. The neuromuscular junction (NMJ) is a chemical synapse between a
neuron and a skeletal muscle. An action potential is initiated by a sufficiently strong enough stimulus which
opens voltage gated sodium (Na+) channels; the depolarization is mainly driven by these channels. The action
potential then travels down the neuron and depolarizes the presynaptic membrane. Next voltage gated calcium
(Ca2+) open and Ca2+ influx on the presynaptic membrane. The SNARE complex then facilitates the vesicles to
fuse with the pre synaptic membrane. The vesicles release acetylcholine (ACh) into the synaptic cleft. On the
postsynaptic membrane (motor end plate) the ACh binds to its receptor (nicotinic) the binding leads to
depolarization of the postsynaptic membrane. Receptors that are voltage sensitive (voltage-sensitive
dihydropyridine receptors DHPR) associate with ryanodine receptors which leads to the release of Ca2+ from
the sarcoplasmic reticulum and through tropomyosin, myosin and actin action a muscle contraction is achieved.
Within the synaptic cleft acetylcholinesterase breakdown ACh to acetate and choline, the presynaptic
membrane then resynthesises ACh by reuptake of choline (Hall, Hall and Hall, 2021) (Boron and Boulpaep,
2003). Inhibitory concentration (IC50) and effective concentration (EC50) are estimates for drug potency, IC50
are used for antagonistic drugs while EC50 are used for agonistic drugs.
1
, Figure 1: Illustration of the Neuromuscular junction.
In order for the nerve conduction to function properly the wash between each simulation in the experiments is
performed with Normal Krebs which have the ions calcium and magnesium at values of 2mM Ca and 1mM
Mg. Tubocurarine is a skeletal muscle relaxant, which prevents depolarization of the muscle by competing
with ACh which usually binds to the acetylcholine receptors nicotinic. By decreasing the number of receptors
available for acetylcholine it functions as a competitive antagonist. Since this drug is an antagonist the
inhibitory concentration (IC50) is estimated. The drug is commonly used as anesthesia during surgery.
Tetradotoxin is a drug that binds to the voltage gated sodium (Na+) channels in the NMJ, by binding it blocks
the channel. The drug inhibits the important mechanism for producing an action potential. The therapeutic
benefits of this drug is being researched for relieving pain in cancer patients, and another potential use is
relieving headache in patients related to heroin withdrawal. (Bucciarelli et al., 2021)(Song et al., 2011). Since
this drug is an antagonist IC50 is estimated. 4-Aminopyridine is a drug that blocks the potassium K+ channels
in the NMJ which has the function that it increases the length of the stimulus (action potential) and the
neurotransmitter released in the synaptic cleft (Kostadinova and Danchev, 2019)(T. Yanagisawa, N. Taira,
2011). Since this drug is an antagonist IC50 is estimated. The drug is used in patients with multiple sclerosis
(Kostadinova and Danchev, 2019b). Neostigmine is a cholinesterase inhibitor, it increases muscle contraction
and is used to treat myasthenia gravis (PubMed, 2006).
Method:
2
Acknowledgements
In order to obtain the data for this experiment # collected the data from The Virtual Twitch software as
labpartners (table 1).
Abstract:
Estimating and evaluating nerve signals in vitro of a rat hemidiaphragm injected by Tetradoxin, Tubocurarine,
4-Aminopyridine and Neostigmine in The Virtual Twitch software.
Introduction:
Many factors play a part in producing a drug response, however there are some basic responses of the human
body when exposed to drugs. Endogenous signaling is chemical signaling from within our own body that is
called “full agonists” in pharmacology. A drug can be a partial agonist, which only produces partial response
compared to the full agonist, which produces a maximal effect. The potency and efficacy of a drug is also
important when considering the characteristics of a drug. Exogenous and endogenous chemical signaling can
interact with each other and affect the affinity of the binding site of the receptor which in turn affects the overall
response. Competitive antagonist- and irreversible antagonist-drugs, can decrease the number of available
receptors and decrease the maximal response respectively. A graded dose response curve illustrates the intricate
interactions of a biological response. The neuromuscular junction (NMJ) is a chemical synapse between a
neuron and a skeletal muscle. An action potential is initiated by a sufficiently strong enough stimulus which
opens voltage gated sodium (Na+) channels; the depolarization is mainly driven by these channels. The action
potential then travels down the neuron and depolarizes the presynaptic membrane. Next voltage gated calcium
(Ca2+) open and Ca2+ influx on the presynaptic membrane. The SNARE complex then facilitates the vesicles to
fuse with the pre synaptic membrane. The vesicles release acetylcholine (ACh) into the synaptic cleft. On the
postsynaptic membrane (motor end plate) the ACh binds to its receptor (nicotinic) the binding leads to
depolarization of the postsynaptic membrane. Receptors that are voltage sensitive (voltage-sensitive
dihydropyridine receptors DHPR) associate with ryanodine receptors which leads to the release of Ca2+ from
the sarcoplasmic reticulum and through tropomyosin, myosin and actin action a muscle contraction is achieved.
Within the synaptic cleft acetylcholinesterase breakdown ACh to acetate and choline, the presynaptic
membrane then resynthesises ACh by reuptake of choline (Hall, Hall and Hall, 2021) (Boron and Boulpaep,
2003). Inhibitory concentration (IC50) and effective concentration (EC50) are estimates for drug potency, IC50
are used for antagonistic drugs while EC50 are used for agonistic drugs.
1
, Figure 1: Illustration of the Neuromuscular junction.
In order for the nerve conduction to function properly the wash between each simulation in the experiments is
performed with Normal Krebs which have the ions calcium and magnesium at values of 2mM Ca and 1mM
Mg. Tubocurarine is a skeletal muscle relaxant, which prevents depolarization of the muscle by competing
with ACh which usually binds to the acetylcholine receptors nicotinic. By decreasing the number of receptors
available for acetylcholine it functions as a competitive antagonist. Since this drug is an antagonist the
inhibitory concentration (IC50) is estimated. The drug is commonly used as anesthesia during surgery.
Tetradotoxin is a drug that binds to the voltage gated sodium (Na+) channels in the NMJ, by binding it blocks
the channel. The drug inhibits the important mechanism for producing an action potential. The therapeutic
benefits of this drug is being researched for relieving pain in cancer patients, and another potential use is
relieving headache in patients related to heroin withdrawal. (Bucciarelli et al., 2021)(Song et al., 2011). Since
this drug is an antagonist IC50 is estimated. 4-Aminopyridine is a drug that blocks the potassium K+ channels
in the NMJ which has the function that it increases the length of the stimulus (action potential) and the
neurotransmitter released in the synaptic cleft (Kostadinova and Danchev, 2019)(T. Yanagisawa, N. Taira,
2011). Since this drug is an antagonist IC50 is estimated. The drug is used in patients with multiple sclerosis
(Kostadinova and Danchev, 2019b). Neostigmine is a cholinesterase inhibitor, it increases muscle contraction
and is used to treat myasthenia gravis (PubMed, 2006).
Method:
2
