Receptor and the Mode of Action

The site at which the xenobiotic interacts with the organism at the molecular level is particularly important. This receptor molecule or site of action may be the nucleic acids, specific proteins within nerve synapses or present within the cellular membrane, or it can be very nonspecific. Narcosis may affect the organism not by interaction with a particular key molecule but by changing the characteristics of the cell membrane. The particular kind of interaction determines whether the effect is broad or more specific within the organism and phylogenetically. 

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It is amazing to note that complex processes such as drug binding to protein, activation of cells, and observation of syncytial cellular response should apparently so closely follow a model based on these simple concepts. This was not lost on A. J. Clark in his treatise on drug receptor theory The Mode of Action of Drugs on Cells [4] ... 

S. V. Perry. Three Hundred Years of Bacterial Motility, Judith P. Armitage. Talking to Cells-Cell Membrane Receptors and Their Modes of Action, Robin F. Irvine. Mechanisms in Regulation Protein Phosphorylation, Philip J. Randle. Regulation of Expression of Microbial Genes, Patricia H. Clarke. Antibody Specificity and Diversity The Proteins (Part I), Lisa A. Steiner. Author Index. Subject Index. 

Androgens such us icsiusicrune do the reverse, but neither mitogens nor estrogens affect stomach epithelium. The liisis for this selectivity is the presence of. selective steroid aormone receptors in individual tissues. This section pro->ldcs an overview of steroid hormone receptors and their mode of action. ... 

In view of the recent discovery of the similarities of action between picrotoxinin and cyclodiene-type insecticides as described above (3,8), it appears worthwhile to reexamine the structural requirement of picrotoxinin-type convulsants for interaction with the specific picrotoxinin binding site. Another objective of this study is to obtain supporting evidence for the role of the picrotoxinin receptor in the mode of action of cyclodiene-type insecticides by synthesizing compounds that structurally bridge the gap between cyclodiene compounds and picrotoxinin. 

In this section theoretical studies on cephalosporins are discussed that have had as their premise the available facts regarding the chemical steps that these molecules undergo when they exert their antibacterial activity. In fact, the B-lactam antibiotics are ideally suited for quantum pharmacology studies because a great deal is known about their biochemical mode of action and the target receptor sites. The mode of action is discussed in detail elsewhere in these volumes. Research on the interaction of p-lactams with bacterial cell walls is an area not lacking frequent comprehensive reviews of the many impressive advances (see, e.g.. 

Ephedrine, which is not a catecholamine, has weak oral activity as a bronchodilator and although it has some direct action at adrenergic receptors, its predominant mode of action is by displacing norepinephrine from storage vesicules. 2"Agonists which are in use or are under investigation are the result of quests for improved selectivity, retention of potency, oral activity, and longer duration of action. 

Dronabinol (tetrahydrocannabinol), the active principle from cannabis and synthetic cannabinoids, nabilone and levonantradol are effective in treating nausea and vomiting in cancer chemotherapy. The mode of action is unclear but appears to involve cannabinoid CBi receptors. Cannabinoids have been shown to reduce acetylcholine release in the cortex and hippocampus, and have been suggested to inhibit medullary activity by a cortical action. Inhibition of prostaglandin synthesis and release of endorphins may also be involved in the antiemetic effect. A review of trials of dronabinol, nabilone or levonantradol concluded that while the cannabinoids were superior to placebo or dopamine receptor antagonists in controlling emesis... 

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