Time and order -dependent changes in functional and nitric oxide
-mediated dilation during exercise training.
Lash, Julia M., and H. Glenn Bohlen.
Department of Physiology and Biophysics, Indiana University School
of Medicine, Indianapolis, Indiana 46202
APStracts 3:0463A, 1996.
Arterial vessel responses to nitroprusside (NP) and acetylcholine
(ACh) were measured in the spinotrapezius muscle of sedentary (SED)
and treadmill-trained (TR) rats to determine if these endothelial
-dependent (ACh) and -independent (NP) mechanisms contribute to the
training-induced increase in functional vasodilation previously
observed. Control and maximal vessel diameters were similar between
SED and TR. After 8 weeks of training, functional dilation (2, 4, and
8 Hz contractions) was enhanced in all orders of vessels studied
(terminal feed artery - FA, largest arterioles - 1A, and
intermediate-sized arterioles - 2A), but responses to NP were
increased only in FA; responses to ACh were not significantly
increased in any vessel order. After 16 weeks of training, functional
dilation had regressed in TR such that only the FA response to 4Hz
was significantly elevated relative to SED. However, the FA and 1A
responses to NP were significantly greater in TR than SED, as were
the 1A and 2A response to ACh. These results show a dissociation of
functional dilation and NP or ACh mediated responses, as well as age
-dependent interactions, a time-dependent progression, and vessel
order specificity in the adaptations to training.
Received 20 May 1996; accepted in final form 25 September 1996.
APS Manuscript Number A475-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996