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Noninvasive assessment of chronotropic and inotropic response to preferential beta‐1 and beta‐2 adrenoceptor stimulation
Author(s) -
Corea Luigi,
Bentivoglio Maurizio,
Verdecchia Paolo,
Motolese Mario,
Sorbini Carlo Augusto,
Grassi Vittorio,
Tantucci Claudio
Publication year - 1984
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1038/clpt.1984.111
Subject(s) - chronotropic , salbutamol , inotrope , medicine , heart rate , hemodynamics , blood pressure , agonist , ejection fraction , anesthesia , cardiology , heart failure , receptor , asthma
The relative chronotropic and inotropic activity of preferential β 1 ‐ and β 2 ‐ adrenoceptor Stimulation was investigated in seven healthy male subjects in a randomized within‐subject, single‐blind study. Two doses of β 1 selective agonist prenalterol (1 mg/hr or 2 mg/hr) and of β 2 ‐selective agonist salbutamol (300 µg/hr or 600 µg/hr) were infused intravenously in four separate sessions, with intervals of at least 48 hr between sessions. At each session cuff blood pressure and heart rate (HR) were measured and some hemodynamic information on the inotropic state were derived by echocardiography. Both prenalterol and salbutamol induced increases in HR, but tachycardia was greater after salbutamol, whereas the positive inotropic response to β‐stimulation was greater after prenalterol. At comparable HR rises (prenalterol, from 66.0 ± 5.5 to 72.2 ± 4 bpm; salbutamol, from 64.6 ± 6 to 70.0 ± 7 bpm), inotropic response seemed to be greater after prenalterol than after salbutamol (systolic blood pressure [SBP]: 133.5 ± 8 and 120.7 ± 8 mm Hg; mean velocity of circumferential fiber shortening [Vcf]: 1.54 ± 0.13 and 1.31 ± 0.12 c/s; ejection fraction [EF]: 72.4% ± 5% and 69.5% ± 4%; stroke index: 47.4 ± 4 and 41.7 ± 3 ml/m 2 ). In presence of a chronotropic effect (HR from 64.6 ± 6 to 70.0 ± 7 bpm), the low salbutamol dose did not induce any changes in the indices of inotropism (SBP: from 119.2 ± 6 to 120.7 ± 8 mm Hg; mean Vcf: from 1.28 ± 0.11 to 1.31 ± 0.12 e/s; EF: from 68.1% ± 5% to 69.5% ± 4%; stroke index: from 40.2 ± 3 to 41.7 ± 3 ml/m 2 . On prenalterol, HR increases were accompanied by changes in all the indices of inotropism. Results would appear consistent with animal data in suggesting some heterogeneity of cardiac β‐adrenergic receptors. Inotropic response to β‐stimulation would appear to be mediated mostly by β 1 ‐ adrenoceptors, whereas β 1 ‐ and perhaps β 2 ‐ adrenoceptors share a mediating action on chronotropic response to cardiac β‐adrenoceptor stimulation. Clinical Pharmacology and Therapeutics (1984) 35 , 776–781; doi: 10.1038/clpt.1984.111