TAILIEUCHUNG - Ebook General and molecular pharmacology: Part 2

Part 2 book “General and molecular pharmacology” has contents: Control of drug plasma concentration, drug–receptor interactions- quantitative and qualitative aspects, receptors and modulation of their response, adaptation to drug response and drug dependence, pharmacological modulation of posttranslational modifications, calcium homeostasis within the cells, and other contents. | SECTION 7 PHARMACOLOGICAL CONTROL OF MEMBRANE TRANSPORT 27 ION CHANNELS Maurizio Taglialatela and Enzo Wanke By reading this chapter, you will: • Become familiar with the main principles governing function, structural organization, and classification of ion channels • Know the role(s) played by the main classes of ion channels in different organs, tissues, and cells • Know the clinical applications of drugs interfering with the function of each ion channel class • Learn how functional changes resulting from drug‐ induced modulation of ion channels can be exploited for therapeutic purposes ION CHANNELS AND TRANSPORTERS Eukaryotic cells use about 30% of their energy to maintain the transmembrane gradients of protons (H+), sodium (Na+), potassium (K+), chloride (Cl−), and calcium (Ca2+), an indi­ cation of their paramount importance for cell survival and replication. On purely thermodynamic grounds, transmembrane trans­ port mechanisms can be classified into active and passive. Passive processes transport ions from the side of the mem­ brane with high electrochemical potential to the side with low electrochemical potential. Two types of proteins are responsible for passive ion transport: facilitated transporters and ion channels (Fig. ), with very different transport mechanisms. Substrate binding to the transporter on one side of the membrane induces a conformational change, resulting in exposure of the substrate on the opposite side of the membrane. The substrate concentration gradient provides the energy required for the process; as the substrate movement is coupled to a conformational change of the transporter, the transfer rate is rather low. By contrast, ion channels contain aqueous pores through which permeating ions can flow at very high rates (>106/s, close to the diffusion rate in water), thus generating significant currents that may rapidly change the resting membrane potential (VREST) of a cell. Both these passive processes dissipate the energy

• Y khoa - Dược
• General and molecular pharmacology
• Molecular pharmacology
• Drug plasma concentration
• Qualitative aspects
• Drug dependence
• Calcium homeostasis within the cells
• Essential lexicon
• A short history of pharmacology
• Drug absorption
• Drug metabolism