Decreases in steady-state muscle performance and vessel density in
reduced renal mass hypertensive rats.
O'drobinak, David M., and Andrew S. Greene.
Department of Physiology, Medical College of Wisconsin, Milwaukee,
WI 53226
APStracts 2:0367H, 1995.
In this study we hypothesized that Reduced Renal Mass (RRM)
hypertension which is associated with a chronic reduction in vessel
density, could reduce steady-state muscle performance. Vessel density
and isometric tetanic force from the in situ gastrocnemius-plantaris
-soleus muscle group were studied in age-matched normotensive sham
-operated control and hypertensive reduced renal mass rats on a high
salt (4.0% NaCl) diet (HSS=High Salt Sham, HSRRM=High Salt RRM), and
a low salt (0.4% NaCl) diets (LSS=Low Salt Sham, LSRRM=Low Salt RRM).
The Achilles tendon was isolated and connected to a force transducer.
Peak isometric tension elicited by sciatic nerve stimulation (1/sec x
10 min, 50 imp/sec for 330 ms) was not different between the groups.
In the LSS, HSS, and LSRRM groups tension decreased similarly at 3
min to 375+/-22 g/g, 447+/-26 g/g and 424+/-21 g/g respectively.
Tension was significantly reduced in the HSRRM group (203+/-45 g/g)
relative to LSS, HSS, and LSRRM groups by 3 minutes. These
differences in steady-state tension persisted throughout the
remainder of the experiment. Microvessel density, measured by the
lectin fluorescence technique, was reduced significantly only in the
soleus, plantaris and medial gastrocnemius of the HSRRM. We conclude
that RRM hypertension results in reductions in vessel density
(rarefaction) that are associated with decreased steady-state muscle
performance.
Received 28 September 1994; accepted in final form 7 August 1995.
APS Manuscript Number H876-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 24 August 1995.