Functional consequences of chronic implantation of electrodes for electromyographic studies in the gastrointestinal tract of chickens

The aims of this work were: A) to define the morphological and functional changes induced by chronic implantation of electrodes for electromyographic studies and B) to study the evolution of the gastrointestinal myoelectrical activity after electrode implantation. Four lots of animals were established: birds implanted with 7 and 5 triplets of electrodes in the gastroduodenal area (lots I5 and I7 respectively); sham operated birds (lot SH) and control (lot C). Body weight was not modified by surgery. Food intake, which was transiently decreased, returned to normal within the first week post-implantation. Gastrointestinal transit time (TT) was significantly increased in lots I7 and SH during the first week. In SH birds TT returned to normal in the second week after surgery, whereas in I7 birds this parameter was not normalized until the third week. Apparent hypertrophy of the duodenum was found in lot I7 but not in lots SH and C (P<0.05). Qualitative electromyographical changes were found in lot I7 but not in lot I5, with no morphological changes. The evolution of the electrical signal (frequency and amplitude of spiking) was analyzed in lot I5. Frequency stabilized shortly after surgery (0.8-2 days). In contrast, amplitude increased progressively to reach a steady value 9-18 days after surgery. Our results indicate that the number of electrodes implanted for electromyographical studies may induce significant morphological as well as motor changes in the gastrointestinal tract. Thus there should be as few electrodes as possible in order to avoid the changes mentioned above. The pattern of the electrical signal vaires with time, so that electromyographical studies should not be undertaken until a steady level in amplitude and frequency is attained. The control of both factors yields a reliable electromyogram. © 1993 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.