CHOLINERGIC ACTIVITY OF INTESTINAL MUSCLE IN-VITRO TAKEN FROM HORSES WITH AND WITHOUT EQUINE GRASS SICKNESS

Equine grass sickness (EGS) is a pan-dysautonomia of horses that invol ves central and peripheral neuronal degeneration and ultimately deplet ion. This is the first reported functional study on the motility of eq uine intestine taken immediately post mortem from horses with EGS. Str ips of smooth muscle from the small intestine of healthy and EGS-affec ted horses were suspended in an organ bath and their motility was meas ured isometrically. The activity of the cholinergic system was studied . Physostigmine enhanced the motility of all muscle strips. Tissues ta ken from horses suffering from acute grass sickness (AGS) had the long est latency before a measurable response could be obtained (p < 0.05). The ileum appeared to be damaged by EGS to a greater extent than the duodenum. For the duodenal strips the enhanced rate of spontaneous con tractions was significant (p < 0.05) for both normal tissue and that a ffected by grass sickness but this was not the case for the ileal stri ps. Muscarinic receptor sensitivity investigation using bethanecol sug gested a hypersensitivity of receptors with AGS material.