AJP - Gastrointestinal and Liver Physiology, Vol 254, Issue 2 162-G167, Copyright © 1988 by American Physiological Society
Neural regulation of duodenal alkali secretion: effects of electrical field stimulation
J. R. Crampton, L. G. Gibbons and W. D. Rees
Department of Gastroenterology, Hope Hospital, University of Manchester School of Medicine, Salford, United Kingdom.
The role of transmitters released from enteric neurons in regulating
bicarbonate secretion by the proximal duodenum has been studied using
electrical field stimulation (EFS). Stripped duodenal mucosa from Rana
catesbeiana was mounted as an intact tube over circular platinum
electrodes, and luminal alkalinization was measured by pH stat titration
before, during, and after EFS. Transmucosal potential difference (PD) was
simultaneously measured before and after EFS by paired electrodes.
Square-wave pulses 50 V, 2 ms in duration, at 10 Hz were delivered in
trains of 0.5 s at 1 Hz for periods of 15 min after stable basal secretion.
This resulted in a 63 +/- 27% increase in alkalinization that returned to
basal values after cessation of the stimulus, without change in
transmucosal PD. Serosal-to-lumen [3H]mannitol flux was not affected.
Repetition of the stimulus resulted in similar responses for as long as the
tissue remained viable. The response to EFS was abolished by tetrodotoxin
(10(-6) M) and veratrine (0.1 mg/ml), indicating that intrinsic neurons
were responsible for mediating the effect. In addition, the effect was
blocked by serosal dinitrophenol (10(-4) M), indicating that the secretory
response occurred by a metabolically dependent process. These results
indicate that alkalinization by proximal duodenum may be controlled by
neurotransmitter release from local enteric neurons.
