Journal of Applied Physiology, Vol 54, Issue 1 244-248, Copyright © 1983 by American Physiological Society
Effects of water immersion on plasma catecholamines in normal humans
M. Epstein, G. Johnson and A. G. DeNunzio
Recent evidence indicates that stimulation of cardiopulmonary receptors in
experimental animals results in a diminution of autonomic nervous system
activity. Water immersion to the neck (NI) results in a preferential
central hypervolemia (CV); thus it might be anticipated that NI would alter
plasma catecholamine levels. Because two earlier studies have yielded
divergent findings, we designed the present study utilizing more updated
methodology to determine whether NI alters plasma catecholamines in normal
humans. Eight normal subjects were studied on two occasions; during a
seated control study (C) and during 4 h of NI. Norepinephrine (NE) and
epinephrine (E) levels, determined by radioenzymatic assay, were measured
hourly. Despite the induction of a marked natriuresis and diuresis
indicating significant CV, NI failed to alter plasma NE or E levels
compared with those of either C or the corresponding prestudy 1.5 h.
Furthermore, the diuresis and natriuresis varied independently of NE. The
current findings suggest that the response of the sympathetic nervous
system to acute volume alteration may differ from the reported response to
chronic volume expansion.
