Modern Receptor Theory Flashcards
Black-box Era
Time when the input was known and the output was observed but what happened between was unknown. Limited by technology.
Horace Davenport
An eminent gastric physiologist who wrote an essay to describe the use of the straw lever and smoked drum technique in teaching physiology to students.
Horace
Horace Davenport
Davenport
Horace Davenport
Straw Lever
Part of early technique to generate dose-response curve. (Similar to drinking straw)
Drum
Part of early technique to generate dose-response curve. (Moving drum used to record muscle contractions.)
Acetylcholine
A neurotransmitter used at neuromuscular junctions, triggering the firing of motor neurons.
AJ Clark
Demonstrated the earliest quantification of receptor action by stimulating isolated tissues in an organ bath with acetylcholine. Also created the occupancy model (quantification enters pharmacology)
ACh
Acetylcholine
Irving Langmuir
Developed the absorption isotherm while studying the absorption of gases on films. A physical chemist who got his doctorate under Nernst in Germany. Works in research labs at General Electro Co. In New York developing better electric bulbs.
Nernst
Need to figure out
Evaporate (Langmuir)
Molecules sticking to the free surface. (Double check)
Condensate (Langmuir)
Molecules being released from the free surface. (Double check)
Equilibrium (absorption isotherm)
The amount of diffusing towards the free surface is balanced by those tending to leave the surface.
Occupation Model
Can be described as empty chairs waiting. Developed by AJ Clark. The addition of quantification to pharmacology.
Equilibrium Law
Another term for the law of mass action
Law of Mass Action
[receptor] + [signalling molecule] <> [signal-receptor complex]. Rate of formation and dissociation equal.
Guldberg and Waage Law
Another name for Law of Mass Action
Guldberg
Part of name for Guldberg and Waage Law of Mass Action. Add more info about him.
Waage
Part of name for Guldberg and Waage Law of Mass Action. Add more info about him.
[receptor]
Includes both free and bound receptors.
Equilibrium (law of Mass action)
Occurs when the formation of new signal-receptor complexes equals the rate at which existing signal-receptor complexes dissociate.
LMA
Law of Mass Action
kON
the rate of formation of new signal receptor complexes. Think of as [S. R.]. An equilibrium constant - think of chemistry. The forward direction, only include products. So just [S.R.]
kOFF
The rate at which molecules unbind from receptors. Think of as [S] [R]. An equilibrium constant. Think of chemistry. Reverse direction, only include products. So just [S] [R]
kD
The equilibrium dissociation constant: [ligand] needed to saturate half of the receptors. kOFF /kON = [S] [R] / [S.R.] You need a certain concentration of ligand to be able to saturate half of the receptors. This measures that. [R] includes bound and unbound receptors. With 50% occupied, [S.R.] will equal half of [R]. Half of the concentration of [S] will be lost to [S.R.]. Therefore 1/2*2 = 1 and kD = [S].
kA
The reciprocal of kD, measures the affinity of receptors for the signalling molecule. kON / kOFF = [S.R.] / [S] [R].
Neurotransmitters kOFF, kON, kD, kA
kOFF - fast reverse (dissociation) rate so high
kON - present in huge concentrations so forward rate slower. low
kD - need large concentration of ligand to achieve 50% effect so high
kA - affinity is low because released in such high concentrations. Low