Analysis of the electrical activity of the canine gastro-oesophageal sphincter in terms of overlapping pulse sequences (Abstract)

Abstract

Basic electrical activity has been recorded from the canine gastro-oesophageal sphincter1,2. In the proximal half there are superimposed fast action potentials which occur with contractions, but in the distal part there is only a basic activity. Using EEG analysis expertise, sinusoidal activity was visible, so a detailed computerized analysis of basic electrical activity in the distal part of the sphincter was made using recently developed techniques3-5. If a sequence of pulses (for example those produced by membrane depolarizations) occurs in such a way that successive pulses overlap each other in time, then the summated wave-form can be approximated by a sinusoidal function. The sinusoid begins at OHz at a phase of plus or minus 90°, rises to some upper frequency limit whilst attenuating in amplitude, and then returns to OHz, increasing in amplitude. The computerized analysis method used in this study detects such sinusoids6. When applied to the basic electrical activity of the canine gastrooesophageal sphincter, recorded in a unipolar derivation, such sinusoids occur at regular intervals. If interpreted in terms of pulse sequences they indicated that several sequences are overlapping at any one moment, such that one begins before another ends. Under normal recording conditions DC terms are removed. However, the analysis technique can test the effect of re-inserting a DC term. This shows that, if the signal does consist of pulse sequences, then these have a specific polarity.