Adrenomedullin and elements of orthostatic competence after 41 h of voluntary submersion in water as measured in four healthy males

Abstract

Four men established a new score (Guinness Book of Records) by staying submersed in thermoneutral water (average diving depth 2.5 m) for 41 h without sleeping. The aim of this study is to measure circulating hormones together with plasma mass density and total protein concentration as indices of plasma volume change to test the hypotheses that (1) blood volume and related hormones are influenced by prolonged water submersion the same way as observed after short-term water immersion, and (2) plasma adrenomedullin levels change in an opposite fashion as with orthostatic stimulation. We also studied effects on cortisol and testosterone levels. Water submersion led to a 19% increase in plasma protein concentration and a 2.5 g/l rise in plasma mass density, corresponding to a 15.6+/-1.1% plasma volume decrease (P=0.00). We therefore individually corrected (c) the observed post-submersion hormone values for plasma volume contraction. Based on this correction, we found a rise of plasma adrenomedullin from 7.9+/-0.9 to 12.5(c)+/-2.3 pg/ml. Aldosterone rose from 123+/-14 to 186(c)+/-24 ng/ml (P=0.029); plasma renin activity increased in all four persons but the type I error was >0.05. Plasma testosterone decreased from 3.5+/-0.4 to 2.2(c)+/-0.6 ng/ml (P=0.009) while plasma cortisol stayed unchanged. The daily salivary cortisol rhythm was preserved. We conclude that long-term water submersion has endocrine as well as plasma volume effects that are opposite to those seen after short-term immersion, and which increases plasma adrenomedullin. Circadian cortisol rhythm seems to be conserved even under extreme circumstances as those of this study.

Neuroendocrine and Psychological Assessment in a Guinness 10 Days Scuba Dive

“…The present study shows that a 240 hour scuba dive does not affect stress parameters, including hormone levels and the cortisol physiological pulsatile secretion. Our data are in line with the recent study by Loder et al [12] performed on four men which established a new Guinness score by staying submersed in thermoneutral water for 41 hours. In these subjects, hormone levels were evaluated.…”

“…Contrarily to that expected, no alterations in circulating hormones including circadian cortisol rhythm were found. According to our and Loder et al data [12], prolonged water submersion does not seem to be a potent stressor, at least in well trained subjects. This observation is also supported by the normal exhaled ethylene values in our divers during the dive period, comparable to those showed in absence of stress condition.…”

Plasma mid-regional pro-adrenomedullin levels are inversely associated with anxiety but unrelated to depression: Results from the observational DIAST-CHF study in patients with cardiovascular risk factors

“…In military veterans with post-traumatic stress disorder, MR-proADM was a significant and independent predictor of mortality after adjustment for B-type natriuretic peptide, cardiovascular risk factors, and diseases such as cancer and sleep apnea (Xue et al, 2012). Anecdotally, one study reported that in four healthy men who established a new score in the Guinness Book of Records by staying submersed in thermoneutral water for more than 40 h, there was a significant rise in plasma ADM concentrations as a consequence of long-term water submersion, while the circadian cortisol rhythm was grossly preserved (Loder et al, 2006). Similar to N-terminal pro-B-type natriuretic peptide (NTproBNP), MR-proADM has been described as a predictor of adverse events in patients with acute myocardial infarction (Khan et al, 2007;Dhillon et al, 2010).…”

Adrenomedullin Expression is Up‐regulated by Acute Hypobaric Hypoxia in the Cerebral Cortex of the Adult Rat

“…This is no surprising as hypobaric hypoxia eventually provokes brain ischemia. Curiously, in a hyperbaric test there was also an increase on AM levels following 41 h of submersion at a depth of 2.5 m (18). The fact that both hypobaria and hyperbaria result in the same response indicates that AM up‐regulation may be a general mechanism to preserve brain integrity.…”