Ion-channel-linked receptors ...........

Ion channel-linked receptors, also known as ligand-gated ion channels, are a type of cell surface receptor that opens or closes in response to the binding of a specific ligand (such as a neurotransmitter). When the ligand binds to the receptor, it triggers a conformational change that allows specific ions (like Na+, K+, Ca2+, or Cl-) to pass through the channel, altering the cell's membrane potential and leading to various cellular responses, such as muscle contraction, neurotransmission, or hormone release. These receptors play a crucial role in the rapid signaling of the nervous system.

1. Ion-channel-linked receptors Presented By-Md Nabeeluddin Karigar M.Pharm, 2 nd Semester Dept.of Pharmacology G Pulla Reddy College of Pharmacy

2. Receptor Receptor- is defined as a macromolecule or binding site located on the surface or inside the effector cell that serves to recognize the signal molecule / drug and initiate the single response to it, Functions of receptors Recognition and binding of the ligand. Propagation of the message. To amplify the signal.

3. Type of Receptor 1 . Ion-channel-linked receptors (Ionotropic receptors) 2. G-protein-linked receptors (Metabotropic receptors) 3. Enzyme-linked receptors (Kinase linked receptor) 4. Nuclear receptor

4. Ion-channel-linked receptors Ligand-gated ion channels (Protein pores), also commonly referred as ionotropic receptors, are a group of transmembrane ion-channel proteins. Which open to allow ions such as Na+, K+, Ca2+, and Cl- to pass through the membrane in response to the binding of a chemical messenger (i.e. a ligand), such as a neurotransmitter. The fundamental role of ion channels in the transmission of electric impulses

5. The Important Gated ion channels are:• Ligand-gated channels• Voltage-gated channels• Ligand-gated channels open in response to the binding of neurotransmitters or other signaling molecules. Voltage-gated channels open in response to changes in electric potential across the plasma membrane.

6. Types of Ligand Gated Ion Channel: (1) Extracellularly activated ligand-gated ion channel : The receptors of the cys-loop family (nicotinic receptors, 5-HT₃, GABAA and GABAC, glycine and serotonin) The glutamate activated cationic channels (NMDA, AMPA, kainate receptors) (2) Intracellularly activated ligand-gated ion channel: ATP sensitive potassium pump Calcium activated-potassium pump, chloride pump G-protein activated potassium pump (CGMP gated ion channels) Ligand-gated channels

7. Ligand Gated Ion Channel: ION CHANNELS AGONIST ANTAGONIST Nicotinic receptor Acetylcholine Glycine Glycine receptor D- tubocurarine Strychnine

8. Voltage-gated channels are a class of transmembrane proteins that form ion channels that are activated by changes in the electrical membrane potential near the channel .

9. Voltage-gated Na* Channel These channels are responsible for the rapid influx of sodium ions during the action potential in nerve, muscle, and endocrine cell.

10. VOLTAGE GATED ION CHANNELS ION CHANNELS AGONIST ANTAGONIST . V. G. SODIUM CHANNEL Aconitine Local anesthetics, anti- arrhythmic drugs

11. Voltage gated Calcium Channels Voltage-gated calcium channels mediate calcium influx in response to membrane depolarization and regulate intracellular processes such as contraction, secretion, neurotransmission. There are several different kinds of voltage-gated calcium channels: L-type : skeletal, smooth, cardiac muscle (contraction) and for aldosterone secretion in endocrine cells of the adrenal cortex. N-type : Pre synaptic terminal and involved in neurotransmission. T-type : neurons, bones(osteocytes). Control the pace-making activity of the SA Node within the heart. R-type : neurons,dentrites .

12. Dysfunction of voltage-gated sodium, potassium and calcium channels, or acetylcholine- and glycine-gated channels may result in may result Neuronal disorders, e.g., epilepsy, episodic ataxia, familial hemiplegic migraine, Lambert-Eaton myasthenic syndrome, Alzheimer's disease, Parkinson's disease, schizophrenia, hyperekplexia

13. Drugs Targeting Ion Channels 1. Verapamil 2. Ziconitide 3. Benzodiazepines 4. Conotoxin 5. Lidocaine Other drugs are: Amlodipine, Nimodipine, Nifedipin, Lidocaine etc.. Most of them are used as anaesthetics, to cure epilepsy, treat hypertension

14. THANK YOU