Variations in the plasma concentration of atrial natriuretic factor across 24 hours.
There is little information available concerning the presence or absence of a normal variation in the circulating concentration of atrial natriuretic hormone throughout a 24 h period. We have examined this in 8 normal subjects (aged 23-35 years) on a fixed 120 mmol Na+ diet. Circulating levels of ANH, plasma renin activity, serum aldosterone and serum cortisol were determined two-hourly during 24 h in a supine position. There was a significant change in the concentration of each of these four hormones during the study period (P less than 0.05). ANH: peak 8.5 (22.00 h), nadir 4.0 (12.00 h) (pmol/l); PRA: peak 1.7 (04.00 h), nadir 0.8 (22.00 h) (microgram.l-1.h-1); aldosterone: peak 350 (14.00 h), nadir 143 (22.00 h) (pmol/l); cortisol: peak 346 (08.00 h), nadir 51 (22.00 h) (nmol/l). Peak plasma ANH occurred at 22.00 h and with the exception of times 20.00 h and 10.00 h this value was significantly higher than all the other time means (P less than 0.05). The only other significant differences were between plasma ANH at 20.00 h and 06.00 h, 08.00 h, 12.00 h and 14.00 h, respectively (P less than 0.05). From midnight until 18.00 h, there was no significant difference between any of the time means. There was a peak in PRA at 04.00 h, while peak serum aldosterone and serum cortisol occurred at 14.00 h and 08.00 h, respectively. This study suggests that ANH may display a diurnal rhythm. Our findings provide further physiological evidence that plasma ANH and PRA may have a reciprocal relationship.
McCance
D R
DR
Sir George E. Clark Metabolic Unit, Royal Victoria Hospital, Belfast, Northern Ireland.
Roberts
G
G
Sheridan
B
B
McKnight
J A
JA
Leslie
H
H
Merrett
J D
JD
Atkinson
A B
AB
D000328:Adult; D000450:Aldosterone / Q000097:blood; D009320:Atrial Natriuretic Factor / Q000097:blood*; D002940:Circadian Rhythm; D004651:Employment; D015444:Exercise; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D008297:Male; D011187:Posture; D012083:Renin / Q000097:blood
D000450:Aldosterone; D009320:Atrial Natriuretic Factor; D012083:Renin; D006854:Hydrocortisone