Pharmacology of Autonomic Nervous System - 3rd Medicine
42 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary pharmacological effect of prazosin?

  • Reduction in heart rate
  • Bronchoconstriction
  • Increased blood pressure
  • Treatment of hypertension (correct)
  • Which drug is classified as a β1-selective adrenergic blocker?

  • Propranolol
  • Doxazosin
  • Atenolol (correct)
  • Yohimbine
  • Which of the following medications has a combined α1-antagonist and β-antagonist action?

  • Labetalol (correct)
  • Metoprolol
  • Nebivolol
  • Idazoxan
  • What undesirable effect is associated with β2 blockade?

    <p>Bronchoconstriction</p> Signup and view all the answers

    In investigating the pharmacological effects, why is a pithed rat chosen for study?

    <p>To simplify interpretation by suppressing reflexes</p> Signup and view all the answers

    What defines a drug as an agonist?

    <p>It has both receptor affinity and efficacy.</p> Signup and view all the answers

    Which statement accurately describes partial agonists?

    <p>They can act like antagonists when full agonists are present.</p> Signup and view all the answers

    What distinguishes competitive antagonists from noncompetitive antagonists?

    <p>Competitive antagonists bind to the same site as the agonist, while noncompetitive antagonists do not.</p> Signup and view all the answers

    What effect do inverse agonists have on signal transduction?

    <p>They decrease the rate of signal transduction.</p> Signup and view all the answers

    How do antagonists exert their effects on agonists?

    <p>By occupying binding sites on the receptor.</p> Signup and view all the answers

    What does an increase in heart rate generally indicate when simulating with Isoprenaline?

    <p>Increase in cardiac contraction force</p> Signup and view all the answers

    Which drug acts as an antagonist at the β1-AR receptor?

    <p>Propranolol</p> Signup and view all the answers

    In the presence of Propranolol, what is expected to happen to heart rate when administering Isoprenaline?

    <p>Heart rate decreases significantly compared to Isoprenaline alone</p> Signup and view all the answers

    What is the effect of Noradrenaline on arterial blood pressure when administered at a dose of 5 µg/kg?

    <p>Moderate increase in arterial blood pressure</p> Signup and view all the answers

    What is the primary receptor affected by the drug Phenylephrine?

    <p>R α-AR</p> Signup and view all the answers

    Which muscarinic receptor is primarily involved in cardiac inhibition?

    <p>M2</p> Signup and view all the answers

    Which of the following best describes the purpose of administering an antagonist like Atropine in cardiovascular simulations?

    <p>To block parasympathetic effects</p> Signup and view all the answers

    What is a primary therapeutic application of muscarinic agonists?

    <p>Treat urinary retention</p> Signup and view all the answers

    What does the term 'dose-response curve' imply in the context of pharmacology simulations?

    <p>The relationship between drug concentration and therapeutic effect</p> Signup and view all the answers

    When measuring blood pressure in experiments, the absence of an antagonist would likely result in what kind of response to Noradrenaline?

    <p>A more pronounced increase in blood pressure</p> Signup and view all the answers

    What type of receptors are influenced by atropine?

    <p>Muscarinic receptors only</p> Signup and view all the answers

    Which receptor subtype is responsible for the secretion stimulation of gastric digestive glands?

    <p>M1</p> Signup and view all the answers

    Which drug is considered a muscarinic agonist acting through indirect action?

    <p>Edrophonium</p> Signup and view all the answers

    Which of the following is not a therapeutic application of muscarinic antagonists?

    <p>Induction of miosis</p> Signup and view all the answers

    Which agent is specifically categorized as a muscarinic receptor antagonist with antispasmodic properties?

    <p>Hyoscine</p> Signup and view all the answers

    Which of the following effects is associated with M3 muscarinic receptor activation?

    <p>Vasodilation</p> Signup and view all the answers

    What is the primary effect of β3 adrenergic receptors?

    <p>Lipolysis and thermogenesis</p> Signup and view all the answers

    Which adrenergic agonist is selective for β1 receptors?

    <p>Dobutamine</p> Signup and view all the answers

    Which of the following actions is primarily associated with α1 adrenergic receptors?

    <p>Vasoconstriction</p> Signup and view all the answers

    Which of the following drugs would not induce positive inotropic effects?

    <p>Propranolol</p> Signup and view all the answers

    Which pharmacological effect does adrenergic stimulation NOT participate in?

    <p>Increased salivary secretion</p> Signup and view all the answers

    Which adrenergic antagonist is specifically α1-selective?

    <p>Prazosin</p> Signup and view all the answers

    Which indirect sympathomimetic agent acts by inhibiting neurotransmitter uptake?

    <p>Cocaine</p> Signup and view all the answers

    Which of the following effects is NOT a result of β2 receptor activation?

    <p>Increased cardiac output</p> Signup and view all the answers

    What was the impact on blood pressure when administering 2 μg/kg of noradrenaline without an antagonist?

    <p>Slight increase</p> Signup and view all the answers

    What is the purpose of injecting an antagonist before administering noradrenaline?

    <p>To evaluate the antagonist's effect on noradrenaline-induced changes</p> Signup and view all the answers

    What was the recorded effect of administering 5 μg/kg of noradrenaline with an antagonist on blood pressure?

    <p>ABP decreased significantly</p> Signup and view all the answers

    During the heart rate experiments, what was the first dose of noradrenaline that was injected?

    <p>50 μg/kg</p> Signup and view all the answers

    What is the highest dosage of noradrenaline administered in the second heart rate experiment?

    <p>500 μg/kg</p> Signup and view all the answers

    What was the antagonist dosage used in the experiments on heart rate and blood pressure?

    <p>10 mg/kg</p> Signup and view all the answers

    What are the outcomes observed from the final high dose of noradrenaline (100 μg/kg)?

    <p>Combined increase in heart rate and blood pressure</p> Signup and view all the answers

    Which of the following is NOT a step included in the experimentation process for heart rate measurement?

    <p>Administer different dosages of antagonist first</p> Signup and view all the answers

    Study Notes

    Pharmacology of Autonomic Nervous System

    • Course: 3rd Medicine
    • Academic Year: 2024/25
    • Professor: Vittoria Carrabs PhD

    Agonists and Antagonists

    • Agonists: Drugs that bind to receptors and activate them, leading to a full or partial response.
    • Antagonists: Drugs that bind to receptors but do not activate them, preventing activation by agonists. They block receptor activation.

    Agonist and Antagonist Definitions

    • Efficacy: The ability of a drug to initiate a cellular effect (intrinsic activity).
    • Agonists: Drugs with both receptor affinity and efficacy.
    • Partial agonists: Drugs with receptor affinity but lacking efficacy, having a submaximal response. In the presence of a full agonist, a partial agonist acts like an antagonist.
    • Antagonists: Drugs with receptor affinity but lacking efficacy. They have common components for binding but only agonists have the structure required for efficacy.
    • Inverse agonist: Decreases the rate of signal transduction.

    Types of Agonists

    • Full agonists: Produce the maximal response possible in a tissue, demonstrating maximal efficacy.
    • Partial agonists: Produce a submaximal response. In the presence of a full agonist, they act as antagonists.
    • Inverse agonists: Decrease the rate of signal transduction.

    Types of Antagonists

    • Competitive antagonists: Bind to the same site as the agonist on the receptor, but are reversibly bound.
    • Non-competitive antagonists: Block the agonist site irreversibly (usually via covalent bonding).

    Central and Peripheral Nervous System

    • Nervous system is divided into Central Nervous System (CNS) and Peripheral Nervous System (PNS).
    • CNS includes the brain and spinal cord, responsible for processing information and directing responses.
    • PNS transmits information between the CNS and the rest of the body. It is further subdivided into Somatic nervous system and Autonomic nervous system.
    • Somatic nervous system controls voluntary actions involving skeletal muscles.
    • Autonomic nervous system controls involuntary responses, such as regulating internal organs and glands.

    Cholinergic System

    • Muscarinic Receptors: Involved in many functions like gastric secretion, vasodilation, bladder contraction, bronchoconstriction, ocular and cardiac functions. Muscarinic receptors contain three different types (M1, M2, M3).
    • Nicotinic receptors: Located in neuromuscular junctions, with specific subtypes (Nm and Nn) important for skeletal muscle contraction and autonomic ganglia.

    Muscarinic Agonists

    • Direct action: Pilocarpine, Cevimeline, Bethanechol.
    • Indirect action: Inhibitors of acetylcholinesterase to increase muscarinic and nicotinic activation.
    • Therapeutic applications: Reduce tachycardia, treat glaucoma (due to agonist induced miosis), treat urinary retention, and paralytic ileus.

    Muscarinic Antagonists

    • Competitive antagonists of muscarinic receptors (also called parasympatholytics).
    • High doses can block nicotine receptors.
    • Therapeutic applications: Treat bradycardia after myocardial infarction, pre-anesthesia, antispasmodic (GI hypertonia or urinary hypertonia) and antidote for acetylcholinesterase inhibitors (like insecticides).
    • List of examples of compounds: Atropine, Glycopyrronium, Hyoscine, Ipratropium, Tropicamide, Cyclopentolate, Darifenacin, Solifenacin, Tolterodine

    Adrenergic System

    • Alpha-1 (α1): Involved in vasoconstriction, GI smooth muscle relaxation, salivary secretion, and hepatic glycogenolysis.
    • Alpha-2 (α2): Inhibits neurotransmitter release, involves platelet aggregation, vascular smooth muscle contraction, and reduction of insulin release.
    • Beta-1 (β1): Increases cardiac rate and force.
    • Beta-2 (β2): Involved in vasodilation, bronchodilation, relaxation of visceral smooth muscle, hepatic glycogenolysis, and muscle tremor.
    • Beta-3 (β3): Involved in lipolysis and thermogenesis, bladder detrusor muscle relaxation.

    Adrenergic Agonists

    • Classification: Direct-acting (selective and non-selective), Indirect-acting, Mixed-acting (releasing agents, uptake inhibitor or co-mimetics, MOA, COMT, and some others). Examples include Adrenaline, Noradrenaline, Isoprenaline, Dopamine, Phenylephrine, α₁-Phenylephrine, α2-Clonidine, B1-Dobutamine, and B2-agonists).
    • Therapeutic effects: Treatment of bradycardia or cardiac arrest. Prevent or control local bleeding (vasoconstriction). Treatment for anaphylactic shock, nasal and ocular decongsestants, prolonged local anesthesia, and hypertension.

    Adrenergic Antagonists

    • Classification: α-antagonists (non-selective, α1-selective, and α2-selective), and β-antagonists (non-selective, β₁-selective, β₂-selective, and mixed). Examples include prazosin, atenolol, propranolol, and labetalol.
    • Actions: α action (e.g. prazosin), treatment in high blood pressure and heart failure, and β actions (e.g. propranolol), reduced strength and heart rate; bronchoconstriction can be an undesirable effect.
    • Therapeutic use for hypertension, tachycardia, or arrhythmias.

    Objectives

    • Investigate and demonstrate pharmacological properties of drugs, (acting on autonomic nervous system, heart or blood vessels. Assess in vivo HR and BP variation in anesthetised animals).
    • Understand practical drug uses and potential toxicities affecting adrenergic receptors.

    CVS Rat Cardiovascular System

    • Simplification methodology (using a denervated and unmedicated rat to avoid carotid artery baroreceptor reflexes).
    • Key parameters (e.g., arterial blood pressure (ABP), left ventricular pressure (LVP), venous blood pressure (VBP), cardiac contraction force, heart rate (HR)).

    Drug List and Receptor Affinity

    • Includes a list of drugs (e.g., Acetylcholine, Adrenaline, Noradrenaline, Phenylephrine, Salbutamol, Atropine, Phentolamine, Prazosin, Propranolol), and their affinities (agonist or antagonist) for specific receptors (muscarinic, nicotinic, α-adrenergic, β1-adrenergic, β2-adrenergic.

    Exercises

    • Detailed instructions for simulating various pharmacologic effects on the rat model, both with and without the intervention of an antagonist. The exercises cover the effects of different doses of Noradrenaline and Acetylcholine.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Description

    This quiz covers the pharmacology of the autonomic nervous system, focusing on agonists and antagonists. It explores definitions, efficacy, and the mechanisms by which these drugs interact with receptors. Perfect for 3rd-year medical students to assess their understanding of this critical topic.

    More Like This

    Use Quizgecko on...
    Browser
    Browser