title: Biphasic changes in heart performance with food restriction in rats.
abstract: To examine effects of food restriction resembling very-low-calorie dieting on heart performance, normal rats were fed 25% of ad libitum food intake for 14 days. Although heart weight decreased (P < 0.05) after 5 days, left ventricular systolic pressure as well as rates of pressure development and fall were increased (P < 0.05) at 7 days and decreased (P < 0.05) after 14 days. Systolic and diastolic blood pressures were also increased from 5 to 7 days and decreased after 14 days. The increased hemodynamic performance of heart was associated with a raised plasma norepinephrine concentration, which peaked at day 7 of food restriction; epinephrine concentration was increased (P < 0.05) also at day 7. An increased catecholamine synthesis was indicated by the raised (P < 0.05) plasma dopamine beta-hydroxylase activity at 3 days, but this was decreased (P < 0. 05) at 14 days. The concentration of dopamine in the heart was increased (P < 0.05) at 2-14 days, of norepinephrine at 7-14 days, and of epinephrine at 10 and 14 days. Food restriction thus appears initially to be associated with an enhanced catecholamine influence on the heart and is followed by a depressed cardiac performance.
authors.affiliation: Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, and Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
authors.forename: K A
authors.initials: KA
authors.lastname: McKnight
authors.forename: H
authors.initials: H
authors.lastname: Rupp
authors.forename: K S
authors.initials: KS
authors.lastname: Dhalla
authors.forename: R E
authors.initials: RE
authors.lastname: Beamish
authors.forename: N S
authors.initials: NS
authors.lastname: Dhalla
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D002395:Catecholamines / Q000502:physiology; D004032:Diet; D004299:Dopamine beta-Hydroxylase / Q000378:metabolism; D002149:Energy Intake / Q000502:physiology; D005508:Food Deprivation / Q000502:physiology*; D006321:Heart / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism; D009638:Norepinephrine / Q000097:blood / Q000378:metabolism / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
chemical_list: D002395:Catecholamines; D004299:Dopamine beta-Hydroxylase; D009638:Norepinephrine