title: Effects of water immersion on sympathoadrenal and dopa-dopamine systems in humans.
abstract: Water immersion to the neck increases central blood volume and evokes a marked diuresis and natriuresis. The present study examined simultaneously effects of water immersion on activities of three endogenous systems thought to participate in sodium homeostasis: the sympathetic nervous system, the atrial natriuretic peptide system, and the renal dopa-dopamine system. Hourly urine collections and antecubital venous blood samples were obtained from 10 normal subjects before, during, and after sitting in a water-immersion tank for 3 h; four control subjects were studied while seated without immersion. Urine volume was increased by more than threefold after 1 h of immersion (from 1.2 +/- 0.2 ml/min at baseline to 5.9 +/- 0.7 ml/min, P less than 0.001) and peaked during the second hour. Urinary sodium excretion increased by more than twofold (from 103 +/- 17 mu eq/min at baseline to 196 +/- 36 mu eq/min at 1 h, P less than 0.001) and peaked during the third hour. Plasma levels and urinary excretion of norepinephrine (NE) and epinephrine were suppressed consistently during immersion (P less than 0.05). There was a marked, prompt, and sustained increase in plasma levels of immunoreactive atrial natriuretic factor (irANF) from 6.9 +/- 1.9 pg/ml baseline to 17.3 +/- 4.3 pg/ml at 1 h (P less than 0.001). Urinary excretion of dopa, dopamine, and 3,4-dihydroxyphenylglycol, a neuronal metabolite of NE, changed in a triphasic pattern, with decreased excretion during the first hour of immersion (P less than 0.01), small but consistent increases during the next 2 h, and decreased excretion, to below baseline, during recovery (P less than 0.01 for dopa and dopamine).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Hypertension-Endocrine Branch, National Heart, Lung, and Blood Institute, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland 20892.
authors.forename: E
authors.initials: E
authors.lastname: Grossman
authors.forename: D S
authors.initials: DS
authors.lastname: Goldstein
authors.forename: A
authors.initials: A
authors.lastname: Hoffman
authors.forename: I R
authors.initials: IR
authors.lastname: Wacks
authors.forename: M
authors.initials: M
authors.lastname: Epstein
mesh_terms: D000311:Adrenal Glands / Q000502:physiology*; D000328:Adult; D009320:Atrial Natriuretic Factor / Q000097:blood; D001826:Body Fluids / Q000378:metabolism; D001834:Body Water / Q000378:metabolism; D002395:Catecholamines / Q000097:blood / Q000652:urine; D004295:Dihydroxyphenylalanine / Q000378:metabolism* / Q000652:urine; D004298:Dopamine / Q000378:metabolism* / Q000652:urine; D004573:Electrolytes / Q000378:metabolism; D006801:Humans; D007101:Immersion; D007668:Kidney / Q000378:metabolism; D008297:Male; D012964:Sodium / Q000378:metabolism; D013564:Sympathetic Nervous System / Q000502:physiology*
chemical_list: D002395:Catecholamines; D004573:Electrolytes; D004295:Dihydroxyphenylalanine; D009320:Atrial Natriuretic Factor; D012964:Sodium; D004298:Dopamine