Drugs receptors for

Simple mathematical calculations by the first pharmacologists in the 1930s indicated that structurally specific drugs exert their action in very small doses and do not act on all molecules of the body but only on certain ones, those that constitute the drug receptors. For example, Clark [407] calculated that ouabain applied to the cells of the heart ventricle, isolated from the toad, would cover only 2.5% of the cellular surface. These observations prompted Clark [407,408] to apply the mathematical approaches used in enzyme kinetics to the effects of chemicals on tissues, and this formed the basis of the occupancy theory for drug-receptor interaction. Thus, pharmacological receptor models preceded accurate knowledge of receptors by many years. 

Table 3. Equilibrium Dissociation Constants for Drug—Receptor Complexes In Vitro...

It has become almost an article of faith among both pharmacologists and medicinal chemists that drugs (and for that matter, hormones) owe their action to interaction with some receptors. 

A classic example of where definitive experimental data necessitated refinement and extension of a model of drug-receptor interaction involved the discovery of constitutive receptor activity in GPCR systems. The state of the art model before this finding was the ternary complex model for GPCRs, a model that cannot accommodate ligand-independent (constitutive) receptor activity. 

Colquhoun, D. (1973). The relationship between classical and cooperative models for drag action. In A symposium on drug receptors, edited by H. P. Rang, pp. 149-182. University Park Press, Baltimore. 

As noted in Chapter 1, the most simple and theoretically sound model for drug-receptor interaction is the Langmuir adsorption isotherm. Other models, based on receptor behavior (see Chapter 3), are available. One feature of all of these models (with the exception of some instances of the... 

Uncompetitive antagonism, form of inhibition (originally defined for enzyme kinetics) in which both the maximal asymptotic value of the response and the equilibrium dissociation constant of the activator (i.e., agonist) are reduced by the antagonist. This differs from noncompetitive antagonism where the affinity of the receptor for the activating drug is not altered. Uncompetitive effects can occur due to allosteric modulation of receptor activity by an allosteric modulator (see Chapter 6.4). 

Rational design, 148-149, 152 Real-time assays, 83, 88 Receptor(s). See also Drug receptors affinity for, 6, 63 allosteric model of, 143 Clark s work, 3 classical model of, 44-45 concept of, 2-4 conformations, 13-14, 13 Of conservation equation for, 76 constitutive activity of, 49-51 coupling of, 27 definition of, 2 desensitization of, 34 efficacy for, 6... 

Anxiolytics are drugs used for the treatment of anxiety disorders. Apart from benzodiazpines, a frequently used anxiolytic is the 5HT1A (serotonin) receptor agonist buspiron, which has no sedative, amnestic or muscle-relaxant side effects, but whose action takes about a week to develop. Furthermore, it is less efficaceous than the benzodiazepines. Buspiron s mechanism of action is not fully understood. 

The pharmacological and/or adverse effects of a drug can be reversed by co-administration of drugs which compete for the same receptor. For example, an opioid receptor antagonist naloxone is used to reverse the effects of opiates. Drugs acting at the same site with opposite effects also can affect each other, e.g. the reduction in the anticoagulant effect of warfarin by vitamin K. 

Drug-Receptor Interaction. Figure 2 Relationships between affinity and efficacy with different agonist response patterns, (a) For partial agonists, differences in maximal responses between agonists relate to differences in efficacy. Differences in the location parameter of the concentration-response curve (potency) indicate differences in affinity, (b) For full agonists, differences in potency indicate differences in either affinity, efficacy or both. 

EEG is the abbreviation for Electroencephalogram. Potency Drug-Receptor Interaction... 

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