title: Age-related decline in beta adrenergic and adenosine A1 receptor function in the heart are attenuated by dietary restriction.
abstract: Previously published reports from this laboratory have shown that the antiadrenergic effect of adenosine A1 agonists declines with age in the rat heart [ J Mol Cell Cardiol 29:593-602] and that this decline may be caused by a decrease in coupling between adenosine A1 receptors (AdoA1R) and guanine nucleotide-binding proteins [ Circ Res 81:1065-1071]. Dietary restriction (DR; 60% calories of ad libitum) has been shown to attenuate age-related changes in cellular signal transduction pathways. Therefore, the present study investigated whether DR altered the age-related changes in AdoA1R-mediated function in senescent rat hearts. Ventricular membranes were isolated from the hearts of ad libitum (AL) fed and DR male F344 rats that were 6, 12 and 24 months of age. In AL rats, there was an age-related decline in isoproterenol (ISO)-stimulated adenylyl cyclase when compared with the 6-month-old rats. The decline in ISO-stimulated cyclase was attenuated in DR animals. In AL rats, inhibition of ISO-stimulated adenylyl cyclase by the AdoA1R agonist, N6-p-sulfophenyladenosine (SPA) decreased with age. In DR rats, the age-related decline in inhibition was attenuated. Previous results from this laboratory indicated that in AL fed rats, there was an age-related decrease in the percentage of high-affinity binding sites for SPA, from 55% at 6 months to 23% at 24 months. Diet restriction attenuated this age-related shift in high-affinity binding sites so that the percentage of high-affinity sites at 24 months was 42%. Our results suggest that DR maintains AdoA1R function by preventing a loss of high-affinity AdoA1R sites.
authors.affiliation: Department of Pharmacology, MCP Hahnemann School of Medicine, Allegheny University of the Health Sciences, Philadelphia, Pennsylvania 19129, USA.
authors.forename: E
authors.initials: E
authors.lastname: Gao
authors.forename: D L
authors.initials: DL
authors.lastname: Snyder
authors.forename: J
authors.initials: J
authors.lastname: Roberts
authors.forename: E
authors.initials: E
authors.lastname: Friedman
authors.forename: G
authors.initials: G
authors.lastname: Cai
authors.forename: A
authors.initials: A
authors.lastname: Pelleg
authors.forename: J
authors.initials: J
authors.lastname: Horwitz
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000367:Age Factors; D000818:Animals; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D004032:Diet / Q000009:adverse effects*; D019204:GTP-Binding Proteins / Q000378:metabolism; D006321:Heart / Q000187:drug effects*; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D011943:Receptors, Adrenergic, beta / Q000187:drug effects* / Q000378:metabolism; D018047:Receptors, Purinergic P1 / Q000187:drug effects* / Q000378:metabolism
chemical_list: D000318:Adrenergic beta-Agonists; D011943:Receptors, Adrenergic, beta; D018047:Receptors, Purinergic P1; D005576:Colforsin; D000242:Cyclic AMP; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases; D007545:Isoproterenol