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Effects of propranolol treatment on left ventricular function and intracellular calcium regulation in rats with postinfarction heart failure
Author(s) -
Litwin Sheldon E,
Katz Sarah E,
Morgan James P,
Douglas Pamela S
Publication year - 1999
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1038/sj.bjp.0702701
Subject(s) - medicine , propranolol , heart failure , inotrope , cardiology , contractility , diastole , myocardial infarction , isometric exercise , blood pressure
Chronic treatment with beta‐adrenergic blocking agents can improve survival in patients with heart failure. The mechanisms underlying the beneficial effects and whether these effects are generalizable to ischaemic heart failure are unresolved. We performed echocardiographic‐Doppler examinations in rats ( n =28) 1 and 6 weeks after myocardial infarction (MI) or sham surgery. Rats were randomized to no treatment or propranolol (500 mg/l in drinking water) after the first echocardiogram. Isometric contractions and intracellular Ca transients were recorded simultaneously in noninfarcted left ventricular (LV) papillary muscles. Untreated MI rats had significant LV dilatation (10.6±0.4 * vs 8.9±0.3 mm, MI vs control), impaired systolic function (fractional shortening=11±2 * vs 38±2%), and a restrictive LV diastolic filling pattern. MI rats receiving propranolol had similar LV chamber sizes (10.6±0.5 mm) and systolic function (13±2%). The propranolol treated animals had higher LV end‐diastolic pressures (27±2 * vs 20±3 mmHg) and a more restricted LV diastolic filling pattern (increased ratio of early to late filling velocities and more rapid E wave deceleration rate). Contractility of papillary muscles from untreated MI rats was depressed (1.6±0.3 vs 2.4±0.5 g mm −2 ). In addition, Ca transients were prolonged and the inotropic response to isoproterenol was blunted. Propranolol treatment did not improve force development (1.6±0.3 g mm −2 ) or the duration of Ca transients during isoproterenol stimulation. Chronic propranolol treatment in rats with postinfarction heart failure did not improve LV remodeling or systolic function. LV diastolic pressures and filling patterns were worsened by propranolol. Treatment also did not produce appreciable improvement in contractility, intracellular Ca regulation or beta‐adrenergic responsiveness in the noninfarcted myocardium.British Journal of Pharmacology (1999) 127 , 1671–1679; doi: 10.1038/sj.bjp.0702701