Journal of Applied Physiology, Vol 49, Issue 3 471-475, Copyright © 1980 by American Physiological Society
Renal blood flow in miniature swine during +GZ stress and anti-G suit inflation
M. H. Laughlin, W. M. Witt and R. N. Whittaker Jr
The effects of +GZ acceleration stress on renal blood flow were studied in
chronically instrumented, conscious miniature swine. Renal blood flow was
determined using the radiolabeled (46Sc, 85Sr, 141Ce, and 125I) microsphere
technique (29 animals) and Doppler-principle flow probes (1 animal). The
results obtained with the microsphere technique indicate that +GZ exposure
with anti-G suit support caused decreases in renal blood flow throughout
the kidney, and that renal blood flow remains decreased for 1-10 min after
+GZ stress. Medullary blood flow appeared to recover after +GZ exposure
more rapidly than cortical blood flow. The flow probe data also indicate
that +GZ stress with or without anti-G suit support results in decreases in
renal blood flow, and that anti-G suit inflation in the absence of +GZ can
also cause significant decreases. We conclude that the reductions in renal
blood flow observed in miniature swine, during +GZ stress with anti-G suit
support, may be due to a combination of direct anti-G suit interference and
+GZ-induced reflex increases in alpha-constrictor sympathetic tone to the
renal vascular bed.
