Cold-sensitive mechanoreceptors with afferent C-fibres in the sheep duodenum.

The effect of changes of temperature on the impulse activity of duodenal mechanoreceptors with afferent C-fibres was studied in acute electrophysiological experiments in chloralose-anaesthetised sheep. The impulse activity of 4 tension receptor units increased when the duodenal mucosa was cooled over the range 0-39 degrees C. The impulse activity of 10 tension receptors was reduced when the mucosa was cooled. Temperature changes between 39 degrees C and 52 degrees C did not alter the discharge pattern of either type of tension receptor response. An additional unit, which may have been associated with pyloric circular muscle, was excited by cooling over the temperature range 0-39 degrees C. This unit was insensitive to compression and was excited by close-intra-arterial injections of pentagastrin, nor-adrenaline, prostaglandin F2a and prostaglandin E2. The cold-sensitivity of mechanoreceptors in the duodenal muscularis externa may play a role in the reflexes regulating gastric emptying in experimental situations when duodenal chyme is cold.