Drug Receptor Interactions

Molecules (eg. As drugs, hormones, neurotransmitters), which bind to receptors are called ligands. The bond can be specifically and reversibly. A ligand may activate or inactivate a receptor. An activation can increase or decrease a particular cellular function. Each ligand is capable of interacting with several subtypes of the receptor. If anything, there are few drugs that are absolutely specific for a receptor, or subtype, but most are relatively selective. Selectivity refers to a large extent on the physico-chemical binding of a drug to cellular receptors. Selectivity is the degree to which a drug is applied at a predetermined location relative to other locations.

Receptors on the cell surface membrane or within the cytoplasm localized (see table: Some types of physiological and drug-receptor proteins). There are macromolecules that are involved in the chemical signal transmission being between and within cells. Activated receptors directly or indirectly regulate cellular biochemical processes (eg., Ion conductivity, phosphorylation of proteins, DNA transcription, enzymatic activity). Molecules (eg. As drugs, hormones, neurotransmitters), which bind to receptors are called ligands. The bond can be specifically and reversibly. A ligand may activate or inactivate a receptor. An activation can increase or decrease a particular cellular function. Each ligand is capable of interacting with several subtypes of the receptor. If anything, there are few drugs that are absolutely specific for a receptor, or subtype, but most are relatively selective. Selectivity refers to a large extent on the physico-chemical binding of a drug to cellular receptors. Selectivity is the degree to which a drug is applied at a predetermined location relative to other locations. Some types of physiological and drug-receptor proteins type structure localization in the cell ion channels Examples of several subunits var model = {thumbnailUrl: ‘/-/media/manual/professional/images/rx_physiologic_drug_receptor_proteins_a_de.gif?la=de&thn=0&mw=350 ‘|| ‘/-/media/manual/professional/images/rx_physiologic_drug_receptor_proteins_a_de.gif?la=de&thn=0’ imageUrl: ‘/-/media/manual/professional/images/rx_physiologic_drug_receptor_proteins_a_de.gif?la=de&thn=0’, title: ” description: ” credits ”, hideCredits: true hideTitle: true hideDescription: true}; var panel = $ (MManual.utils.getCurrentScript ()) Closest ( ‘image-element-panel.’). ko.applyBindings (model, panel.get (0)); Cell surface transmembranös acetylcholine (nicotinic) GABAA glutamate glycine G-protein-coupled receptors var model = {thumbnailUrl ‘/-/media/manual/professional/images/rx_physiologic_drug_receptor_proteins_b_de.gif?la=de&thn=0&mw=350’ || ‘/-/media/manual/professional/images/rx_physiologic_drug_receptor_proteins_b_de.gif?la=de&thn=0’ imageUrl: ‘/-/media/manual/professional/images/rx_physiologic_drug_receptor_proteins_b_de.gif?la=de&thn=0’, title: ” description: ” credits ”, hideCredits: true hideTitle: true hideDescription: true}; var panel = $ (MManual.utils.getCurrentScript ()) Closest ( ‘image-element-panel.’). ko.applyBindings (model, panel.get (0)); Cell surface transmembranös acetylcholine (muscarinic) ?- and ?-adrenergic receptor proteins eicosanoids protein kinases var model = {thumbnailUrl ‘/-/media/manual/professional/images/rx_physiologic_drug_receptor_proteins_c_de.gif?la=de&thn=0&mw=350’ || ‘/-/media/manual/professional/images/rx_physiologic_drug_receptor_proteins_c_de.gif?la=de&thn=0’ imageUrl: ‘/-/media/manual/professional/images/rx_physiologic_drug_receptor_proteins_c_de.gif?la=de&thn=0’, title: ” description: ” credits ”, hideCredits: true hideTitle: true hideDescription: true}; var panel = $ (MManual.utils.getCurrentScript ()) Closest ( ‘image-element-panel.’). ko.applyBindings (model, panel.get (0)); Cell surface transmembranös growth factors insulin peptide hormones transcription factors var model = {thumbnailUrl: ‘/-/media/manual/professional/images/rx_physiologic_drug_receptor_proteins_d_de.gif?la=de&thn=0&mw=350’ || ‘/-/media/manual/professional/images/rx_physiologic_drug_receptor_proteins_d_de.gif?la=de&thn=0’ imageUrl: ‘/-/media/manual/professional/images/rx_physiologic_drug_receptor_proteins_d_de.gif?la=de&thn=0’, title: ” description: ” credits ”, hideCredits: true hideTitle: true hideDescription: true}; var panel = $ (MManual.utils.getCurrentScript ()) Closest ( ‘image-element-panel.’). ko.applyBindings (model, panel.get (0)); Cytoplasm steroid hormones thyroid hormone vitamin D GABA = ?-aminobutyric acid; GDP = guanosine diphosphate; GTP = guanosine triphosphate. The ability of a drug to affect a particular receptor, depends on the affinity of the drug (probability that the drug at any time a receptor occupied) and the intrinsic activity from (intrinsic efficacy – the extent to which a ligand activates a receptor, and leads to a cellular response). Affinity and activity of a drug is determined by its chemical structure. The pharmacological effect is also determined by the duration of the existing drug-receptor complex ( “residence time”). The lifetime of the drug-receptor complex is influenced by dynamic processes (conformational) that control the rate of drug binding and dissociation of the target substance. A longer “residence time” explains a prolonged pharmacological effect. Among the drugs with a long “residence time” include finasteride and darunavir. A longer “residence time” can potentially be detrimental if it extends the toxicity of a drug. In some receptors temporary pharmaceutical use for the desired pharmacological effect results, whereas a longer application is toxic. Physiological functions (e.g., as contraction, secretion) are usually regulated by a variety of receptor-mediated mechanisms, and there may be a number of steps (z. B. receptor coupling, several intracellular second messengers [second messenger]) between the initial drug receptor interaction and the final tissue or organ response be connected. Therefore, a number of different drug molecules can be commonly used to produce the same desired response. The ability to bind to a receptor, is influenced by external factors and by intracellular regulatory mechanisms. The base density of receptors and the effectiveness of the stimulus-response mechanisms vary from tissue to tissue. Drugs, aging, genetic mutations and diseases can increase the number and binding affinity of the receptors (upregulation) or decrease (down-regulation). For example, clonidine alpha2 receptors can down-regulate. Therefore, the rapid withdrawal of clonidine hypertensive crises may result. Long-term therapy with beta-blockers increases the density of the beta receptors. Therefore can lead to abrupt discontinuation severe hypertension or tachycardia. The up- and down-regulation of receptors influences the adaptation of drug (eg. B. Desensitization, tachyphylaxis, tolerance, acquired resistance, hypersensitivity after discontinuation). Ligands bind to specific regions of the molecular receptor macromolecule, so-called recognition sites. The binding site for the drug may be the same or different than that for the endogenous agonist be (hormone or neurotransmitter). Agonists that bind to adjacent or other bodies of a receptor are also called allosteric agonists. Non-specific drug binding, d. H. of molecular sites which are not intended as receptors (eg., plasma proteins) may also take place. By binding to such non-specific sites, such as the binding of serum proteins, the drug is inactivated, because thereby the binding of the drug is inhibited to the receptor. Unbound drugs are for binding to receptors available and so have an effect. Agonists and antagonists agonists activate receptors to produce the desired signal. Conventional agonists increase the proportion of activated receptors. Inverse agonists stabilize the receptor in its inactive conformation and function similarly to competitive antagonist (s. Agonists and antagonists). Many hormones, neurotransmitters (eg. As acetylcholine, histamine, norepinephrine) and drugs (e.g., morphine, phenylephrine, isoproterenol, benzodiazepines, barbiturates) act as agonists. Antagonists prevent receptor activation. The prevention of activation has many effects. Antagonists enhance cellular function if they block effects of a substance that normally reduces the cellular function. Antagonists reduce the cellular function if they block effects of substances that normally increasing the cellular function. Receptor antagonists can be classified as reversible and irreversible. Reversible antagonists dissociate easily from their receptors, irreversible antagonists form a stable, permanent or virtually permanent chemical bond with its receptor (z. B. at alkylation). Pseudoirreversible antagonists dissociate slowly from its receptor. In a competitive antagonism to binding of an antagonist to the receptor prevents the binding of the agonist to the receptor. In the non-competitive antagonism agonist and antagonist can be simultaneously attached, however, decreases the binding of the antagonist or prevents the action of the agonist. When reversible competitive antagonism agonist and antagonist form short-term bonds with the receptor, and it represents an equilibrium between agonist, antagonist and receptor. Such antagonism can be overcome by increasing the concentration of the agonist. For example, if naloxone (an opioid receptor antagonist that is structurally morphine very similar) will be given shortly before morphine, it blocks the effects of morphine. However, the competitive antagonism by naloxone can be overcome if more morphine is given. Structural analogues of agonists often have the characteristics of agonists and antagonists. Such drugs are called partial agonists (weakly potent agonists) or agonist-antagonists. For example, pentazocine activates opioid receptors, but also blocks the activation by other opioids. Therefore pentazocine results in opioid effects, but makes the effect of other opioids destroyed when they are given as long as pentazocine is still bound. A drug that acts as a partial agonist in a tissue can act in other than full agonist.

Health Life Media Team

Leave a Reply