AJP - Gastrointestinal and Liver Physiology, Vol 259, Issue 3 511-G517, Copyright © 1990 by American Physiological Society
Time-series analysis of myoelectric cycling of sphincter of Oddi: evidence of cycling during fed state
M. E. Zenilman, J. Parodi, E. Spitznagel and J. M. Becker
Department of Surgery, Washington University School of Medicine, St. Louis, Missouri 63110.
The sphincter of Oddi (SO) in the fasted opossum exhibits spontaneous
cyclic spikeburst activity that is temporally related to the interdigestive
migrating myoelectric complex (MMC) of the small intestine. After feeding,
the cyclic activity is apparently disrupted. Our aim was to use time-series
analysis to mathematically describe the periodic behavior of the fasted
state and to determine whether this periodicity is present after feeding.
Five opossums were chronically prepared with bipolar electrodes secured to
the SO. With the animals fasted and conscious, myoelectric activity was
recorded for at least two MMC cycles after which they were fed 170 kcal of
cream. Spikeburst frequency data were analyzed by fast Fourier transform
(FFT) and by digital band-pass filtering. Results from FFT analysis showed
an intense low-frequency peak during the fasted state which persisted but
was markedly depressed during the fed state. Analysis of the data after
filtering also showed persistent sinusoidal activity at the MMC frequency
after feeding, although the waveform was significantly depressed by both
peak-to-peak amplitude and root mean square amplitude analysis. Recovery to
normal fasting cyclic behavior with recovery of both FFT and filtered data
was observed. We conclude that in the opossum the cyclic nature of the SO
myoelectric activity observed during the fasted state persists after
feeding, but is inhibited and masked by an increase in overall spikeburst
activity.
