Hypertension, Vol 19, 482-487, Copyright © 1992 by American Heart Association
F Magrini, P Reggiani, M Ciulla, R Meazza and G Branzi
The purpose of this experiment was to study the impact of simulated
microgravity and of chronic removal of hydrostatic pressure gradients on
blood pressure maturation and body growth in rats. A special device was
developed in our laboratory to transfer prolonged "dry" water immersion (a
technique that has been used for training astronauts under hypogravic
conditions) to six Sprague-Dawley test rats (immersion-G group). The time
course of heart rate, systolic blood pressure, urinary output, and body
weight was monitored from weaning to maturity and then compared with those
responses from six sex- and age-matched Sprague- Dawley rats grown in a
gravity environment (group G). A downward shift in systolic blood pressure
and body weight maturation curves was observed in immersion-G rats from the
age of 60 days. Cessation of dry water immersion produced a gradual,
significant rise in systolic blood pressure but not in body weight to
control values. No marked changes in heart rate and urinary output between
G and immersion-G rats were noticed throughout the investigation. Our
results provide indirect evidence that an interference in the natural
history of blood pressure maturation was introduced by immersion, which
dissociated the effects of body weight increase during growth from the
effects of ageing per se. It is concluded that the physiological increase
in systolic blood pressure during growth is partly gravity-dependent.
ARTICLES
Prolonged water immersion. Effects on blood pressure maturation in normotensive rats
Cattedra di Medicina Interna, Universita di Cagliari, Milan, Italy.
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