title: Chronic propranolol treatment promotes left ventricular dilation without altering systolic function after large myocardial infarction in rats.
abstract: In rats with chronic myocardial infarction (MI), we have examined the effects of prolonged beta-adrenergic blockade with propranolol on left ventricular (LV) performance, weight, and volumes. Sham-operated rats and rats with large MI (greater than 30%) were evaluated. Four groups of rats were studied: control, sham-operated (n = 12); control, MI (n = 12); propranolol (500 mg/L of drinking water)-treated, sham-operated (n = 10); and propranolol treated, MI (n = 10). Treatment was started 3 weeks after coronary ligation. After 5-6 weeks, LV, systemic arterial, and right atrial pressures in addition to aortic blood flow before and during volume loading were measured. LV pressure-volume relations were measured ex vivo. The rats with chronic MI demonstrated expected decreases in LV systolic performance and increased LV end-diastolic and right atrial pressures. Propranolol had no independent effect on LV systolic pressure, LV end-diastolic pressure, resting cardiac index, stressed cardiac index during volume loading, peak developed aortic pressure during aortic occlusion, or ejection fraction index in either sham-operated or infarcted rats; however, heart rate was decreased. LV weight/body weight was 2.17 +/- 0.04 mg/g in control sham-operated rats, which was not different from the propranolol-treated sham-operated rats (2.09 +/- 0.04 mg/g). The LV weight/body weight was increased (p less than 0.01) to 2.21 +/- 0.08 mg/g in the propranolol-treated MI group from 1.94 +/- 0.06 mg/g in the control MI group. The LV pressure-volume relation was not altered by propranolol in the sham-operated rats but was shifted to the right by MI.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Internal Medicine, Veterans Administration Medical Center, Portland, Oregon 97201.
authors.forename: R G
authors.initials: RG
authors.lastname: Gay
authors.forename: T E
authors.initials: TE
authors.lastname: Raya
authors.forename: S
authors.initials: S
authors.lastname: Goldman
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D006332:Cardiomegaly / Q000473:pathology; D002908:Chronic Disease; D004305:Dose-Response Relationship, Drug; D006352:Heart Ventricles / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology; D006439:Hemodynamics / Q000187:drug effects; D008297:Male; D009203:Myocardial Infarction / Q000473:pathology / Q000503:physiopathology*; D011433:Propranolol / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013599:Systole / Q000187:drug effects*; D013997:Time Factors
chemical_list: D011433:Propranolol