Changes in jejunal myoelectrical activity during exercise in fed untrained dogs.
Seven female dogs (15-20 kg) were instrumented with seven bipolar electrodes sutured at 3-cm intervals to the serosal surface of the proximal jejunum and were exercised at different intensities and durations on a motor-driven treadmill. Slow-wave frequency increased (P less than 0.05) from preexercise control during prolonged (90 min) exercise and during recovery after short-term exercise (30 min) at 70% heart rate reserve (HRR). These changes were associated with an increase in core temperature. Spike-burst frequency (SBF) increased (P less than 0.05) with moderate exercise (50% HRR), but the magnitude was small. When exercise was extended beyond 30 min and during all recovery periods, SBF decreased significantly. Exercise produced migrating myoelectrical complexes in three experiments and less dramatic pattern changes characterized as "clustered contractions" (regular spike bursts preceded and followed by the absence of spike bursts) in at least nine other experiments. We conclude that exercise does alter jejunal myoelectrical activity, but myoelectrical patterns may be more important in explaining exercise-induced gastrointestinal symptoms than changes in spike-burst frequency or duration.
Kenney
M J
MJ
Department of Exercise Science, University of Iowa, Iowa City 52242.
Flatt
A
A
Summers
R W
RW
Brown
C K
CK
Gisolfi
C V
CV
D000818:Animals; D001831:Body Temperature; D004285:Dogs; D004594:Electrophysiology; D005260:Female; D005502:Food; D006339:Heart Rate; D007583:Jejunum / Q000294:innervation / Q000502:physiology*; D005082:Physical Exertion; D013997:Time Factors