AJP - Regulatory, Integrative and Comparative Physiology, Vol 258, Issue 6 1424-R1430, Copyright © 1990 by American Physiological Society
Cardiovascular, renal, and endocrine responses in male quadriplegics during head-out water immersion
F. Tajima, S. Sagawa, J. Iwamoto, K. Miki, B. J. Freund, J. R. Claybaugh and K. Shiraki
Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan.
The present study was undertaken to determine the relative influence of the
action of the central nervous system on the mechanism of
water-immersion-induced diuresis by comparing physiological responses of
quadriplegic (QP) and normal subjects. After overnight fasting seven male
QP subjects with complete cervical cord transections (C5-C8) and six normal
men were tested before, during, and after 3 h of head-out immersion (HOI)
in thermoneutral water (34.5-35.0 degrees C). The reversible increase in
urine flow and the total urine volume (309 +/- 53 ml in 3 h) in QP subjects
were comparable with that of the normal subjects (318 +/- 96 ml in 3 h).
While osmolal excretion was increased in QP subjects, its magnitude was
less when compared with that of normal subjects. Instead, the increased
urine flow in QP subjects was characterized by increased glomerular
filtration rate (GFR) and free water clearance, in contrast to a
predominantly osmotic diuresis with no changes in GFR in the normal
subjects. The HOI elevated (P less than 0.05) systolic pressure only in QP
subjects, whereas the increase in cardiac output was the same in both
groups. While plasma renin activity and aldosterone responses to HOI in QP
subjects were comparable with those of normal individuals, plasma atrial
natriuretic factor (ANF) in QP subjects was twofold higher (P less than
0.05) during HOI, and the approximately threefold increase in ANF (P less
than 0.05) in QP subjects due to HOI was the same as that of normal
subjects.(ABSTRACT TRUNCATED AT 250 WORDS)
