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Chapter 6: Introduction to Autonomic Pharmacology
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A 3-year-old child has been admitted to the emergency department having swallowed the contents of 2 bottles of a nasal decongestant. The active ingredient of the medication is a potent, selective α-adrenoceptor agonist drug. Which of the following is a sign of α-receptor activation that may occur in this patient?
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(B) Cardiac acceleration (tachycardia)
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(C) Pupillary dilation (mydriasis)
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(D) Renin release from the kidneys
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(E) Vasodilation of the blood vessels of the skin
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Mydriasis can be caused by contraction of the radial fibers of the iris; these smooth muscle cells have α receptors. All the other listed responses are mediated by β adrenoceptors (Table 6–4). The answer is C.
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