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52 terms

BPS 321 part 2

STUDY
PLAY
intrinsic activity
property of agonist drugs; ability to affect(alter or influence) signal activity in target cells; related to, but not identical to efficacy
inverse agonist
an agonist that produces cellular responses by decreasing constitutive signal activity
in vivo
inside the intact living organism. pertaining to the whole animal or patient
Ka
index of antagonist potency ex vivo; the average free concentration of a competitive antagonist sufficient to double the EC50 of an agonist acting on the same receptor. Ka= - log (pA2)
ligand
collective term for any drug, neurotransmitter, or hormone that binds with defined affinity to specific receptors
pA2
logarithmic form of the index of competitive antagonist potency; the molar concentration of competitive antagonist required to double the EC50 of the agonist.
partial agonist
an agonist whose intrinsic activity is not sufficient to produce maximum achievable responses in cells, organs, or tissues
pharmacology
the study of drugs, their actions, and their mechanisms of action
pharmacokinetics
the study of the processing of drugs or toxins by the body, including ADME
pD2
logarithmic form of the index of agonist potency; the molar concentration of agonist required to produce 50% of the maximal response of a cell, tissue, or organ to antagonist. pD2= - log (EC50)
PKC
protein kinase C, a signal enzyme protein that is activated by diacylglycerol
PLC
phospholipase C, enzyme associated with receptors and that catalyzes the conversion of inositol phosphates into downstream signal molecules
pharmacodynamics
the study of interactions between drugs, either agonists or antagonists, and their receptors
potency
at the cellular level, relationship between the concentration of a drug (agonist or antagonist) accessible to cellular receptors and the magnitude of the response of the cell, tissue, or organ to that drug. in vivo: relationship between the dose of a drug and the magnitude of a response. amount of drug required to produce a response of a defined magnitude
quantal response
a response to a drug that is either present or absent. refer to graded response
receptor
a molecule- mostly commonly a protein on or in a cell- that binds with defined affinity to a ligand and mediates it biologial effects
signal
a series of enzymatic reactions or molecular interactions that are functionally linked to receptors and that mediated and account for the cellular response to agonists on those receptors
stimulatory effect
an increase in the activities of the cells, tissues, or organs in response to binding of ligands to their reecptors. also called stimulatory response
stimulatory receptor
a receptor whose activation ultimately results in an acceleration or intensification of the activities of the cell, tissue, or organ
toxicology
the study of toxins, their actions, and their mechanism of action
toxin
any chemical substance that, in sufficient quantities, exerts harmful effects on biological systems.
Adenylate Cyclase
A signal enzyme associated with GPCRs that converts ATP to cyclic adenosine monophosphate (cAMP), a downstream signal molecule
Affinity
Relationship between the free concentration of a ligand in the vicinity of its receptors and the fraction of the total number of accessible receptors that are bound to the ligand. Both agonists and antagonists have affinity for theirs receptors.
Agonist
A ligand that activates a receptor upon binding to it. Agonists possess the property of intrinsic activity,
Agonist potency
At the cellular level, the relationship between the concentration of an agonist in the vicinity of its receptors and the magnitude of the ensuing response of the cell, tissue, or organ; at the whole-animal or patient level, the relationship between the dose of an agonist drug and the magnitude of the observable response.
Constitutive signal
Basal signal activity in a cell that is present even in the absence of receptor activation by an agonist
Drug
Any non-nutrient chemical substance that, in sufficient quantities, alters the activities of biological systems.
Drug Concentration
Amount of a drug dissolved in blood or other solutions in patients or whole animals, or in perfusing or bathing solutions in isolated cells or organs (expressed in units such as moles per liter [M] or micrograms per deciliter [ug/dL]).
Antagonist
A ligand that binds to a receptor but does not activate it. lack intrinsic activity.
Antagonist potency
At the cellular level, the relationship between the concentration of an antagonist in the vicinity of its receptors and the magnitude of the inhibition of agonist effects on those receptors; at the whole animal or patient level, the relationship between the dose of an antagonist drug and the magnitude of the observable response
Drug Dose
Amount of a drug administered to a patient or whole animal (expressed in mg, mg/Kg of body weight, or square meters of surface area, etc.)
EC_50_
Index of agonist potency ex vivo. It is the antilog of the pD_2_
ED_50_
Index of potency in vivo (in whole animals or patients) of an agonist or antagonist drug.
Ex vivo
outside the body or isolated from the body, usually isolated cells, tissues, or organs.
Effect (response)
Specific and measurable (observable) change in cellular signal or observable response to the agonist.
Effector
Protein or other macromolecule that is an ultimate target of a signal pathway
Endogenous
originating from and acting inside the body (e.g. hormones and neurotransmitters)
Exogenous
Produced, or administered from, outside the body. all drugs, even hormones or neurotransmitters used as drugs are exogenous.
Full agonist
an agonist whose intrinsic activity is sufficient to produce maximum achievable responses in cells, organs, or whole animals or patients.
GPCR
G protein-coupled receptors; a broad category of receptors that are associated with regulatory complexs called G proteins because they bind to GTP and GDP
Graded Response
a response to a drug that is, more or less, or a continuum, e.g. changes in urine production or blood pressure. See quantal response.
Inhibitory effect
A decrease in activities of cells, tissues, or organs in response to binding of ligands to their receptors; also called inhibitory responses.
Inhibitory receptors
A receptors whose activation decreases the activities of the cell, tissue, or organ.
signaling bias
one receptor has different isoforms that will create different responses
functional ligand selectivity
two ligands of similar structure produce diff activities
signal crosstalk
one GPCR signaling pathway will effect another pathway
receptor desensitization
same number of receptors, receptors less sensitive
receptor down regulation
different number of receptors on surface
tachyphylaxis
rapid loss of intrinsic activity (secs/mins)
longer term pharmacodynamic tolerance
delayed loss of activity (hrs/days)
super sensitivity/ receptor upregulation
when antagonist causes more receptors to be on the cell surface because agonists cant downregulate/desensitize them so sudden discontinuation will create an influx of agonists to create a heightened response
cumulative dose response curve
concentration is added on top of existing concentration