U22203 (Respiratory, Renal & Cardiovascular Pharmacology): general guide to coursework marking criteria Q1. Answer should include e.g. pharmacological natures of the reagents, sites of action,...

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U22203 (Respiratory, Renal & Cardiovascular Pharmacology): general guide to coursework marking criteria Q1. Answer should include e.g. pharmacological natures of the reagents, sites of action, relevant receptors occupied and the involvement of any relevant endothelium derived mediators and any relevant major second messengers in dilator mechanisms Q2 Answer should include e.g. pharmacological natures of the reagents, sites of action, relevant receptors occupied and the involvement of any relevant major second messengers in dilator mechanisms Q3. Answer should include e.g. consideration of relevant phase(s) of relevant cardiac action potential/sites of action, relevant receptors occupied and signalling events including the involvement of any relevant second messengers Q4. Answer should include e.g. consideration of chemical as well as pharmacological natures of these reagents Q5. Answer should include e.g. consideration of relevant phases of relevant cardiac action potentials/sites/types of action, relevant receptors occupied and signalling events including the involvement of any relevant second messengers as well as overall rank potency order for these reagents re raising heart rate and force Q6. Answer should include e.g. consideration of relevant phases of relevant cardiac action potentials/sites/types of action, relevant ion channels and relevant mechanisms of excitation-contraction coupling re effects on cardiac force Q7. Answer should include e.g. consideration of pharmacological nature of ouabain, major site and mechanism of action in vitro and relevant related cellular chain of events with significance for cardiac force Q8. Answer should include e.g. consideration of pharmacological nature of verapamil, consideration of relevant phase(s) of relevant cardiac action potential/site(s) of action and mechanism of action, including effects on relevant ion movement(s) Q9. Answer should include e.g. consideration of electrical nature of stimulus and relevant mechanisms of action/outcomes for relevant cardiac ion channels and ion movements and excitability Q10. Answer should include e.g. consideration of pharmacological nature of propranolol and expected interaction with autonomic nervous regulation of cardiac function, as e.g. in a whole organism Q11. Answer should include e.g. consideration of other relevant biological/functional attributes of a whole organism (in vivo) which could affect pharmacological responses, the influence of which would be avoided by using an in vitro preparation Q12. The numerical estimate supplied should represent EC50 in µM NB: references are optional, but not required Microsoft Word - U22203 coursework 2019-2020 re first attempt U22203 (Respiratory, Renal & Cardiovascular Pharmacology): coursework Please submit completed coursework as word document (≤ 1000 words) online by end of Friday, January 10, 2020. NB: Ensure to enter your student number in both filename of submitted document and in document itself. Q1. Briefly describe the mechanism of vasodilation to carbachol and phentolamine in the endothelium-intact, phenylephrine- preconstricted isolated aorta. (10%) Q2. Briefly describe the mechanism of relaxation to salbutamol and atropine in the carbachol-precontracted isolated trachea. (10%) Q3. Briefly explain the effects of acetylcholine on heart rate, at a cellular signalling level, in the isolated perfused heart. (15%) Q4. Comment on why the use of carbachol in place of acetylcholine is sometimes preferred experimentally. (5%) Q5. At a cellular signalling level, how do ß-adrenoceptor agonists raise heart rate and force of contraction in the isolated perfused heart and what is the expected relative order of potency of noradrenaline, adrenaline and isoprenaline with respect to cardiac effects? (20%) Q6. Briefly explain the importance of calcium to both heart rate and force of contraction in the isolated perfused heart. (10%) Q7. Briefly explain the effects of ouabain to raise the force of contraction in the isolated perfused heart. (5%) Q8. Briefly explain how verapamil is able to reduce the force of contraction in the isolated perfused heart. (5%) Q9. Briefly explain how high potassium can arrest the heart in diastole in the isolated perfused heart. (5%) Q10. Describe how the presence of an intact autonomic nervous system might have altered the response to propranolol per se in the isolated perfused heart. (5%) Q11. Apart from an intact nervous system, name two more key, physiologically relevant in vivo features that are typically absent from in vitro preparations. (5%) Q12. Using data in table 1, estimate the EC50 value for carbachol in µM, from a plot of the sigmoidal concentration-response curve. (5%) Table 1. Contraction in the isolated trachea in response to carbachol (CCh) (n=1) Log10 [CCh] (M) in organ bath contraction (g) -8 0 -7.52 0.05 -7 0.3 -6.52 0.5 -6 1.2 -5.52 2.3 -5 3.25 -4.52 3.5 -4 3.5
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Answer To: U22203 (Respiratory, Renal & Cardiovascular Pharmacology): general guide to coursework marking...

Arundhati answered on Jan 09 2021
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Respiratory, Renal & Cardiovascular Pharmacology
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1. Mechanism of vasodilation
Carbachol acts on nicotinic as well as muscarinic receptors, and it is administered to decrease intraocular pressure in treating glaucoma[footnoteRef:1]. Phentolamine generates its therapeutic activities through
blocking alpha-adrenergic receptors and lead to muscle recreation along with the broadening of blood containers. The primary action of phentolamine is vasodilation and selecting alpha-blockers can cause relaxation of systematic vasculature that led to hypotension. The mechanism of action of phentolamine is adrenergic alpha antagonist while carbachol is nicotinic receptors and increase aqueous humor outflow. [1: Ishida H, Saito SY, Horie A, Ishikawa T. Alleviation of mechanical stress-induced allodynia by improving blood flow in chronic constriction injury mice. European journal of pharmacology. 2019 Apr 15;849:67-74.]
2. Mechanism of relaxation
Salbutamol in the mechanism of relaxation increase airflow and provide rapid relief of acute asthma[footnoteRef:2]. The peak of salbutamol is within 30 minutes of administration. It usually acts on beta two adrenergic receptors that are found on smooth muscle airways of lungs. It acts as a functional antagonist for relaxing the airway of spasmogen. Atropine has a relaxation effect at the higher concentration on smooth muscle. It is categorized as an anticholinergic drug and considered as an antimuscarinic agent. It inhibits actions of muscarinic ACH on structures innervated by cholinergic nerves. It is usually used for reducing saliva and other secretions in airways during surgery. [2: Rodríguez‐Ramos F, Andrade‐Moreno MÁ, Alfaro‐Romero A, Balderas‐López JL, Navarrete A. Gnaphaliin A and gnaphaliin B synergize the relaxant effect of salbutamol but not of ipratropium in guinea pig trachea. Journal of Pharmacy and Pharmacology. 2016 Apr;68(4):533-41.]
3. Effects of acetylcholine on heart rate
It is identified that acetylcholine binds to muscarinic receptors and cause a decrease in the heart rate. In isolated heart muscle, acetylcholine depresses atrial contractions but contain the positive inotropic effect on ventricular muscle under specific conditions[footnoteRef:3]. Moreover, neurons are motivated by the parasympathetic nervous system to issue neurotransmitter acetylcholine at synapses in order to decrease heart rate. When the effect of acetylcholine changes in contractility, isoprenaline produce the heart rate activity in the perfused heart. Increased intracellular level generated by ACH may influence the heart rate at a cellular level. ACH released as neurotransmitter from the cranial nerve that results in reducing cardiac rate. [3: Liu Y, Scherlag BJ, Fan Y, Xia W, Huang H, Po SS. Acetylcholine–Atropine Interactions: Paradoxical Effects on Atrial Fibrillation Inducibility. Journal of cardiovascular pharmacology. 2017 Jun 1;69(6):369-73.]
4. Reason of using carbachol instead of acetylcholine
Carbachol is the carbamate ester and ammonium salt that act as a nicotinic acetylcholine receptor and cardiotonic drug. It is primarily used for treating glaucoma and during ophthalmic surgery. It is considered as a potent cholinergic agent...
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