on intestine and of antagonism PHL 313 Lab 2 2 3 The Muscarinic Actions Similar to those of parasympathetic stimulation M1 CNS PNS gastric parietal cells ID: 1038464
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1. 1Effect of cholinergic drugs on intestine and % of antagonism.PHL 313 (Lab. 2)
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3. 3The “Muscarinic Actions” -- Similar to those of parasympathetic stimulation• (M1): CNS, PNS, gastric parietal cells • (M2): conducting tissue • (M3): exocrine glands; smooth muscle
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5. 5Cholinergics agonist Cholinergic agonists (direct acting )AcetylcholineBethanecholPilocarpineCarbacholAnticholinesterases (indirect acting ) reversible :Neostigmine, physostigmine, pyridostigmine Irreversible : (e.g Organophosphates )(isoflurophate, echothiophate )
6. Cholinergic Antagonists[Anticholinergic Agents]Block the actions of acetylcholine at muscarinic or nicotinic cholinoceptors. Cholinergic antagonists competitively inhibit the activity of endogenous Ach.Antimuscarinic agents: inhibit muscarinic receptor-mediated responses. AtropineScopolamineIpratropiumGanglionic-blocking agents: inhibit nicotinic receptor-mediated responses at the ganglia. HexamethoniumPentamethoniumNeuromuscular-blocking agents: inhibit nicotinic receptor-mediated responses at the neuromuscular junction. Non-depolarizing : D-tubocurarineDepolarizing : suxamethonium 6
7. Depolarization1- Resting potential:In order to maintain the cell membrane potential, cells keep a low concentration of sodium ions and high levels of potassium ions within the cell (intracellular). The sodium-potassium pump moves 3 sodium ions out and moves 2 potassium ions in, thus in total removing one positive charge carrier from the intracellular space.2- Depolarization is a positive-going change in a cell's membrane potential, making it more positive, or less negative. In neurons and some other cells, a large enough depolarization may result in an action potential. 3- Hyperpolarization is the opposite of depolarization, and inhibits the rise of an action potential.7
8. Procedure:-1- Add 0.2 ml Nicotine and record the response within 10 seconds then wash.2- Add 0.2 ml C6 wait 2 minutes and add 0.2 ml Nicotine and record the response within 10 seconds then wash.3- Add 0.2 ml Ach and record the response within 10 seconds then wash.4- Add 0.2 ml atropine wait 2 minutes and add 0.2 ml Ach and record the response within 10 seconds then wash.5- Add 0.2 ml BaCl2 and record the response within 10 seconds then wash.6- Add 0.2 ml C6 wait 2 minutes and add 0.2 ml BaCl2 and record the response within 10 seconds then wash.7- Add 0.2 ml atropine wait 2 minutes and add 0.2 ml BaCl2 and record the response within 10 seconds then wash.8- Print the figures and calculate the % of antagonism with agonist (4 equations).
9. 9Effect Of Nicotine & Hexamethonium% of antagonist X1 – X2 * 100 X1 Dil. NicotineHexamethonium (C6)Dil. NicotineWash No Wash X1x2
10. 10Effect Of Ach & Atropine % of antagonist X1 – X2 * 100 X1 Ach AtropineAchWash No Wash X1x2
11. 11Effect Of Bacl2 & Atropine % of antagonist X1 – X2 * 100 X1 Bacl2Hexamethonium (C6)Bacl2Wash No Wash X1x2Wash AtropineNo Wash Bacl2x2
12. Chemicals1- Tyroid solution2- Ach (0.01%)3- Dilute Nicotine (0.01%)4- Hexamethonium (C6) (0.1%)5- Atropine (0.1%)6- Barium Chloride (3%)