Basal and stimulated plasma atrial natriuretic peptide (ANP) concentrations and cardiac ANP contents in old and young rats.
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.
Reckelhoff
J F
JF
Department of Physiology, West Virginia University, Morgantown 26506.
Morris
M
M
Baylis
C
C
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
D012462:Saline Solution, Hypertonic; D009320:Atrial Natriuretic Factor