Hormonal and metabolic responses to electrically induced cycling
during epidural anesthesia in humans.
Kjaer, M., N. H. Secher, J. Bangsbo, G. Perko, A. Horn, T. Mohr, and
H. Galbo.
The Copenhagen Muscle Research Center, Departments of Internal
Medicine TTA and Anaesthesia, Rigshospitalet; Department of Human
Physiology, The August Krogh Institute; Department of Reumatology H,
Bispebjerg Hospital and Department of Medical Physiology, The Panum
Institute, University of Copenhagen, Denmark.
APStracts 3:0145A, 1996.
Hormonal and metabolic responses to electrically induced dynamic
exercise were investigated in eight healthy young males with afferent
neural influence from the legs blocked by epidural anesthesia (25 ml
2% lidocaine) at L3-L4. This caused cutaneous sensory anesthesia
below T8-T9 and complete paralysis of the legs. Cycling increased
oxygen uptake to 1.90+/-0.13 l/min (mean,SE) and fatigue developped
after 22.7+/-2.7 min. Compared to voluntary exercise at the same Vo2
and heart rate, concentrations of blood and muscle lactate (m. vastus
lateralis) as well as plasma potassium increased more, while muscle
glycogen decreased more during electrical exercise. Hepatic glucose
production (Ra) always rose during exercise. However, during
involuntary exercise with sensory blockade it did not match the rise
in peripheral glucose uptake (Rd) and plasma glucose decreased
(p<0.05). Plasma glycerol increased less in electrical vs
voluntary, and FFA and [beta]-hydroxybutyrate decreased only during
electrically induced exercise. Epinephrine, growth hormone, ACTH and
cortisol levels were higher during involuntary vs voluntary exercise
(p<0.05). In conclusion, neural and humoral mechanisms exert
redundant control with regard to responses of catecholami nes and
pituitary hormones (GH and ACTH). In contrast, neural input from
motor centers and feedback from working muscle is important for
glucose production and lipolysis during exercise in humans. Humoral
feedback is apparently not sufficient to trigger normal mobilization
of extramuscular fuel stores.
Received 17 November 1994; accepted in final form 23 January
1996.
APS Manuscript Number A1180-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 27 March 96