title: Basal and stimulated plasma atrial natriuretic peptide (ANP) concentrations and cardiac ANP contents in old and young rats.
abstract: To investigate the ability of the ageing heart to release atrial natriuretic peptide (ANP) we compared the response of awake, trained, chronically catheterized old (20-21 months) and young (4 months) rats to an acute, hypertonic saline challenge. There were no differences between young and old rats in basal plasma concentration of sodium (PNa; old: 141 +/- 3 meq/l; young: 143 +/- 3 meq/l) or ANP (old: 61 +/- 5 pg/ml; young: 67 +/- 12 pg/ml). Five minutes after acute saline challenge, PNa rose in both groups (old: 146 +/- 2 meq/l; young 149 +/- 1 meq/l) and approximately 3-fold increases in plasma ANP levels (182 +/- 24 pg/ml; young: 179 +/- 42 pg/ml). Hearts of old and young rats were assayed for atrial and ventricular ANP content. Atrial ANP levels were similar in old and young rats (13.5 +/- 3.6 vs. 24.9 +/- 8.7 micrograms/g atrial tissue), whereas ventricular ANP content was approximately 4-fold higher in old vs. young rats (153.7 +/- 39.3 vs. 47.5 +/- 6.4 ng/g ventricular tissue). Thus, the ageing rat heart responds equally as well as the young rat to an acute NaCl challenge.
authors.affiliation: Department of Physiology, West Virginia University, Morgantown 26506.
authors.forename: J F
authors.initials: JF
authors.lastname: Reckelhoff
authors.forename: M
authors.initials: M
authors.lastname: Morris
authors.forename: C
authors.initials: C
authors.lastname: Baylis
mesh_terms: D000375:Aging / Q000097:blood / Q000378:metabolism*; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000097:blood / Q000378:metabolism*; D006325:Heart Atria / Q000378:metabolism; D006352:Heart Ventricles / Q000378:metabolism; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D009318:Natriuresis / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage
chemical_list: D012462:Saline Solution, Hypertonic; D009320:Atrial Natriuretic Factor