actions of acetylcholine and nitroprusside. Results (a) Estimate the maximum responses (Emax) and EC50 values for phenylephrine with the two types of arterial ring. Put this data in a single‚ self-explanatory table. Table1. Emax and EC50 values for phenylephrine. Phenylephrine | Emax in grams tension | EC50 in nM | Endothelium intact | 2.2 | 40 | Endothelium denuded | 2.9 | 10 | (c) Estimate the EC50 values for the effects of acetylcholine and
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include an increase in Amyloid β peptides‚ a decrease in the neurotransmitter acetylcholine‚ and the demyelization of the myelin sheath. Throughout the process of aging the concentrations of acetylcholine decrease resulting in irregular lapses of short-term memory. Once acetylcholine is released into the synapse‚ a protein (acetylcholinesterase) breaks it down. Acetylcholinesterase is required to ensure that acetylcholine does not stay in the synapse for an excessive amount of time; if it remains
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Carbachol = cholinomimetic drug that binds and activates the acetylcholine receptor. It is a cholinergic agonist used for treating glaucoma or during ophthalmic surgery. Choline carbamate Positively charged quaternary ammonium compound Not well absorbed in GIT tract and does not cross the BBB Not easily metabolised by cholinesterase 2-5 min onset of action Duration of action 4-8 hours (topical)‚ 24 hours for intraocular administration Parasympathomimetic that sitmulates both muscarinic and
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gravis is a chronic‚ progressive neuromuscular‚ autoimmune disease marked by varying degrees of weakness of the skeletal (voluntary) muscles of the body. The body’s immune system attacks and destroys receptors in the muscles. These receptors bind acetylcholine‚ the neurotransmitter released from motor neurons. (Turkington & Harris‚ 2009) The main calling card of myasthenia gravis is muscle weakness that increases during periods of activity and improves after periods of rest. Muscles that control eye
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into remission or mitigate severe symptoms. In the case of medication‚ there are two classifications of drugs. The first are called anticholinesterases‚ which temporary relieves the symptoms of myasthenia gravis by preventing the breakdown of acetylcholine; the second are called immunosuppressants‚ which stop the body from damaging the neuromuscular junction but will compromise the immune system. As far as surgery‚ doctors recommend thymectomy‚ the removal of the thymus‚ for patients under the age
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vestibulo-ocular reflex (VOR) (Halmagyi‚ 2003; Itoh & Sakata‚ 1991) . These include: Glutamate‚ which maintains the resting discharge of the central vestibular neurons‚ and may control synaptic transmission in all three neurons of the VOR arc; acetylcholine‚ which appears to function as an excitatory neurotransmitter in both the peripheral and central synapses and gamma-Aminobutyric acid (GABA)‚ which is believed to be inhibitory
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14. CHOLINERGIC AGONISTS AND CHOLINESTERASE INHIBITORS CHOLINERGIC AGONISTS Overview “muscarinic receptor agonists” cholinergic agonists are drugs that act on acetylcholine receptors‚ thus causing excitation of the parasympathetic autonomic nervous system there are 2 types of acetylcholine receptors 1) NICOTINIC RECEPTORS - are receptor-mediated ion channels - 3 types RECEPTOR TYPE MUSCLE TYPE GANGLION TYPE LOCATION - neuromuscular junction - sympathetic autonomic ganglia - parasympathetic autonomic
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1/03/13 Introduction to Pharmacology II Targets of Drug Action March 5 How do drugs work? | Nearly all drugs act by interfering or inhibiting natural processes which are required for normal physiological function but which may have been disrupted by disease. | Paul Ehrlich 1845-1915 | Observed that certain chemicals or drugs bound in a selective manner to some but not all cells. He recognised that the cells must have chemical recognition sites for these drugs. The concept of a “receptor”
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Desensitization‚ homologous or heterologous Spare receptors -1- OVERVIEW OF AUTONOMIC PHARMACOLOGY PHARMACOLOGICAL (NOT ANATOMICAL) DIVISION OF PNS: Cholinergic vs. Adrenergic Cholinergic: All preganglionic and parasympathetic postganglionic Acetylcholine is the neurotransmitter at ganglia‚ nmj‚ and muscarinic tissue synapses Adrenergic: Postganglionic sympathetic neurons (most). Norepinephrine is the transmitter Exceptions: Cholinergic transmission in sympathetic system - all ganglia‚ adrenal
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Anticholinergic (Parasympatholytic) Bronchodilators History and Development The prototype anticholinergic agent is atropine‚ which is found naturally in the plants Atropa belladonna and the Datura species. Scopalamine is also extracted from the belladonna plant‚ and both atropine and scopolamine are called belladonna alkaloids. |Agent |Date |Event | |Belladonna
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