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July 1972

A Standardized Isoproterenol Sensitivity Test: The Effects of Sinus Arrhythmia, Atropine, and Propranolol

Author Affiliations

Nashville, Tenn

From the Division of Clinical Pharmacology, departments of medicine and pharmacology, Vanderbilt University School of Medicine, Nashville, Tenn. Dr. Rangno is now with Montreal General Hospital, Montreal.

Arch Intern Med. 1972;130(1):47-52. doi:10.1001/archinte.1972.03650010035007

Isoproterenol hydrochloride sensitivity was measured from dose/response curves to rapid intravenous injections as the dose required to increase the heart rate by 25 beats per minute (chronotropic dose25 or CD25). The most accurate assessment of CD25 was achieved by using the three shortest R-R intervals of the electrocardiogram to calculate heart rate before and after administration of isoproterenol to eliminate the effect of sinus arrhythmia. In ten subjects the CD25 appeared to increase with age between 21 and 35. Neither the chronotropic nor hypotensive effects of the CD25 for isoproterenol were affected by atropine sulfate, suggesting that vagal withdrawal does not contribute to the chronotropic effect of this dose. Propranolol hydrochloride increased the CD25 by acting as a competitive antagonist. The test procedure was safe, accurate, reproducible, and convenient for measuring both β-receptor responsiveness and β-adrenergic blockade in man.

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