Chronic and acute volume expansion in normal man: effect on atrial diameter and plasma atrial natriuretic peptide.
Plasma levels of immunoreactive alpha human atrial natriuretic peptide (IR-ANP) and left atrial diameter were measured in 6 normal subjects before and after 6 days of sodium loading using salt supplements and 9-alpha-fluorohydrocortisone. During chronic sodium loading, which increased mean body weight by 1.5 kg and markedly reduced plasma renin and aldosterone levels, plasma IR-ANP increased from 21 +/- 3 to 36 +/- 7 pmol/l (P less than 0.02). Increase in atrial diameter correlated with gains in body weight (r = 0.93, P less than 0.01) but not with increase in plasma IR-ANP. After chronic sodium loading for 6 days, further volume expansion (2 litres of saline infused over 2 hours) significantly increased left atrial diameter but did not affect plasma IR-ANP levels. We conclude that chronic sodium loads increase plasma IR-ANP. However, the failure of further acute atrial distension to increase hormone levels suggests that factors in addition to atrial stretch are important in regulating atrial peptide secretion in man.
Cuneo
R C
RC
Department of Endocrinology, Princess Margaret Hospital, Christchurch, New Zealand.
Espiner
E A
EA
Crozier
I G
IG
Yandle
T G
TG
Nicholls
M G
MG
Ikram
H
H
D000328:Adult; D000450:Aldosterone / Q000097:blood; D009320:Atrial Natriuretic Factor / Q000097:blood / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D006321:Heart / Q000033:anatomy & histology* / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood; D012083:Renin / Q000097:blood; D012964:Sodium / Q000097:blood; D014465:Ultrasonics
D000450:Aldosterone; D009320:Atrial Natriuretic Factor; D012964:Sodium; D012083:Renin; D009638:Norepinephrine