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DrVirgo Forum Junior Topics: 731 Posts: 3487	Feb 09, 2006 - 9:05 AM       #1 49. After taking an overdose of propranolol, a 35-year-old woman develops sinus bradycardia and syncope. In order to stimulate the same second messenger system that is activated by â-adrenergic receptors, which of the following drugs will be most effective to increase her heart rate? A ) ADH (vasopressin) B ) Atrial natriuretic peptide C ) Clonidine D ) Glucagon E ) Phenylephrine
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doc179 Forum Guru Topics: 67 Posts: 1213	Feb 09, 2006 - 9:10 AM       #2 is it D?
lalitha Forum Junior Topics: 9 Posts: 51	Feb 09, 2006 - 7:05 PM       #3 the ans is D
DrVirgo Forum Junior Topics: 731 Posts: 3487	Feb 09, 2006 - 9:06 PM       #4 Are you sure? Glucagon activates Gs and Alpha 1 activates Gq.
robin082006 Forum Hero Topics: 468 Posts: 5028	Feb 09, 2006 - 9:46 PM       #5 E? ADH: V1, V2. indicated for ADH deficiency, Gq ANP: systemic vasodilation, maybe due to decrease the release of sympathetic products Clonidine: Alpha2 agonist, used in hypertension, Gi Glucagon: used in beta blocker intoxication, Gs phenylephrine: alpha 1 agonist, Gq, used as decongestant and mydriasis without cycloplegia
doc179 Forum Guru Topics: 67 Posts: 1213	Feb 09, 2006 - 10:21 PM       #6 I had not understood the question...I think they want us to choose drug to reverse bradycardia by using the same second messenger system as A-adrenergics..If what I have understood now is correct then the ans is E ( phenylephrine)..and if we are asked to use that second messenger system that is used by B-adrenergics then the ans is glucagon
robin082006 Forum Hero Topics: 468 Posts: 5028	Feb 09, 2006 - 10:28 PM       #7 I'm confused too because phenylephrine is not used for such purposes
DrVirgo Forum Junior Topics: 731 Posts: 3487	Feb 09, 2006 - 10:29 PM       #8 Sorry all, I think there may be a typo in the question: I think it should say: 49. After taking an overdose of propranolol, a 35-year-old woman develops sinus bradycardia and syncope. In order to stimulate the same second messenger system that is activated by BETA-adrenergic receptors, which of the following drugs will be most effective to increase her heart rate? A ) ADH (vasopressin) B ) Atrial natriuretic peptide C ) Clonidine D ) Glucagon E ) Phenylephrine Then people who said D) Glucagon are right... Well, alpha receptors are not involved in increase heart rate (alpha 1 is responsible for increasing diastolic pressure and thereby increasing TPR; alpha 2 is to decrease blood pressure and is used in hypertension) Beta 1 is the only one that increases HR… A stimulation of Beta 1 receptors activates a G protein (Gs). Glucagon also has a similar action by activating the same G protein Gs.
Nan Forum Senior Topics: 12 Posts: 159	Sep 09, 2006 - 4:45 PM       #9 Anecdotal evidence suggests a benefit of higher doses of glucagon in the treatment of overdose with beta blockers; the likely mechanism of action is the increase of cAMP in the myocardium, effectively bypassing the inhibitory action of the β-adrenergic second messenger system

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