title: Effects of altitude acclimatization on fluid regulatory hormone response to submaximal exercise.
abstract: To determine the effect of altitude acclimatization on plasma levels of atrial natriuretic peptide (ANP) during submaximal exercise and its relationship with renin and aldosterone, seven male volunteers aged 17-23 yr exercised to exhaustion on a cycle ergometer at 80-85% of their maximum O2 uptake at sea level (SL; 50 m), during 1 h in a hypobaric chamber [acute altitude (AA); 4,300 m], and after 14 or 16 days of residence on the summit of Pikes Peak, CO [chronic altitude (CA); 4,300 m]. Plasma samples taken before exercise, 10 min after the start of exercise, and 5 min postexercise were analyzed for ANP, plasma renin activity (PRA), and aldosterone (ALDO). ANP showed a progressive increase from rest to postexercise [7.49 +/- 1.63 to 11.32 +/- 1.80 (SE) pmol/ml and 6.05 +/- 2.55 to 10.38 +/- 7.20 pmol/ml; P = 0.049, exercise] at SL and AA, respectively, but not at CA (P = 0.039, altitude). Similarly, PRA and ALDO rose from rest to postexercise (P < 0.001, exercise), but the rise in ALDO with exercise was less during AA than during SL and CA (P = 0.002, phase). The decreased ANP levels during exercise after altitude acclimatization, with no change in PRA and ALDO, suggest that ANP has little effect on PRA and ALDO under these conditions.
authors.affiliation: Division of Altitude Physiology and Medicine, US Army Research Institute of Environmental Medicine, Natick, Massachusetts 01760.
authors.forename: P B
authors.initials: PB
authors.lastname: Rock
authors.forename: W J
authors.initials: WJ
authors.lastname: Kraemer
authors.forename: C S
authors.initials: CS
authors.lastname: Fulco
authors.forename: L A
authors.initials: LA
authors.lastname: Trad
authors.forename: M K
authors.initials: MK
authors.lastname: Malconian
authors.forename: M S
authors.initials: MS
authors.lastname: Rose
authors.forename: P M
authors.initials: PM
authors.lastname: Young
authors.forename: A
authors.initials: A
authors.lastname: Cymerman
mesh_terms: D000064:Acclimatization; D000328:Adult; D000450:Aldosterone / Q000097:blood; D000531:Altitude; D000532:Altitude Sickness / Q000097:blood; D009320:Atrial Natriuretic Factor / Q000097:blood*; D001826:Body Fluids / Q000378:metabolism; D004032:Diet; D004573:Electrolytes / Q000378:metabolism; D006801:Humans; D008297:Male; D005082:Physical Exertion; D012083:Renin / Q000097:blood; D012084:Renin-Angiotensin System
chemical_list: D004573:Electrolytes; D000450:Aldosterone; D009320:Atrial Natriuretic Factor; D012083:Renin