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BMS242 - Phys/Pharm of Cells > CNS Pharmacology > Flashcards

Flashcards in CNS Pharmacology Deck (299)
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 Who was the first to demonstrate the usefulness of nitrous oxide as an analgesic in the process of tooth extraction?

Horace Wells


William Morton was known for his use of ether as a volatile anaesthetic during tooth extraction, T or F?



What was J. Simpson’s contribution to general anaesthesia?

He was the first person to demonstrate that chloroform could render patients’ unconscious. Was also deemed the co-discoverer of general anaesthetics


What are the two classes of chemical general anaesthetics?

Inhalational and intravenous


What type of general anaesthetic is NO2?

Inhalational chemical general anaesthetic


Give an example of some intravenous chemical general anaesthetics?

Halogenated hydrocarbons such as isoflurane. Also steroids and barbiturates such as thiopental are also intravenous


Give some examples of physical general anaesthesias?

Low pressure, hypothermia


What is meant by the term surgical anaesthesia?

The point at which patients become unresponsive and unable to sense pain


What evidence is there to suggest that anaesthetics aren’t agonists acting on a receptor?

Steep dose-response curve which isn’t seen in agonist binding. Low pressure can also induce anaesthesia


What is significant about the dose-response curve of general anaesthetics?

They have very steep dose-response curves


What property of general anaesthetics is very closely related to their potency?

Lipid solubility


Describe what is meant by a MAC value and how this relates to the potency of the general anaesthetic?

MAC value – minimum alveolar concentration of anaesthetic to alleviate a response to surgical incision in 50% of patients. The lower the MAC value the higher the potency of the general anaesthetic


What is meant by the oil:gas partition coefficient?

The ease with which a substance dissolves, or partitions into oil


Drugs with a low oil:gas partition coefficient will have a high potency and thus a lower MAC value, T or F?

F – drugs with higher oil:gas partition coefficients will have a high potency and lower MAC values


What is meant by the Meyer-Overton rule?

The effect of an anaesthetic is proportional to the molar concentration of the agent in lipid


What is the effect of general anaesthetics on the plasma membrane?

General anaesthetics lead to a volume expansion in the plasma membrane


What is the impact of general anaesthetics on lipid fluidity?

General anaesthetics increase lipid fluidity


What aspects of the general anaesthetic mechanism of action are explained by the lipid theory?

As antibiotics are thought to lead to a volume expansion of the plasma membrane and an increase in lipid fluidity the lipid theory of antibiotic action accounts for the meyer-overton rule. In addition, the effect of pressure is also explained as we know that a decrease in pressure results in a volume expansion of the lipid membrane and thus will give rise to anaesthesia. Finally this also accounts for the fact that such a diverse range of compound can have anaesthetic effects


What aspects of the general anaesthetic mechanism of action aren’t explained by the lipid theory?

The fact that decreasing temperature can have anaesthetic effects despite the fact that it leads to a decrease in membrane fluidity. It also doesn’t explain that the binding of anaesthetics is saturable, implying a specific interaction with a protein. Finally there is a loss of actions in some compounds that are extremely lipid soluble and being homologous to known anaesthetics


It in fact turned out that the mechanism of action of anaesthetics was a combination of the lipid theory and a protein binding theory, T or F?



What is significant about the binding sites of anaesthetics that have been proven to bind to proteins in the plasma membrane?

General anaesthetic binding sites tend to be in hydrophobic domains deep within the membrane


What type of proteins do general anaesthetics tend to bind to?

Ion channels


Which specific receptor is it known that some general anaesthetics bind to and how does this lead to anaesthesia?

GABAA receptors – inhibition of regions in the central nervous system leading to anaesthesia


Different anaesthetics all interact with the same subunits of the proteins to which they bind, T or F?

F – different anaesthetics bind to different subunits


Where to intravenous anaesthetics tend to bind on the GABAA receptors?

β subunit


Where in the GABAA receptor structure do volatile liquid general anaesthetics tend to bind?

The interface between the α and β subunits


What is the function of the two-pore-domain potassium channels?

Regulate the excitability of neurons


How do general anaesthetics that bind to the two-pore-domain potassium channels exert their effects?

Increase the excitability of the channels and make the firing of actions potentials less likely


Explain ketamine’s anaesthetic effect?

Ketamine is an NMDA receptor antagonist and is known as a dissociative anaesthetic which prevents the action of excitatory glutamate


What type of protein is targeted by isoflurane and how does this cause anaesthesia?

Voltage-gated Na+ channels – inhibition of these channels prevent depolarisation and action potential generation