In vitro Evaluation Techniques for Gastrointestinal Motility

Abstract:

In vitro techniques involve isolation of pieces of tissue taken from a recently killed animal and are kept alive in a suitable salt solution for biological evaluation of investigational drugs. Different parts of the small intestine are used in the pharmacological experiments. Various types of patterns of intestinal movements are involved in the physiological progression of chyme along the gastrointestinal tract (GIT). Peristaltic movements are myogenic and mainly initiated by local reflexes. Any substance affecting the motility can disturb functionality of the GIT. The study of gastrointestinal (GI) motility may be helpful in (1) determining alteration in motility (2) evaluating effect of pathological condition on GI transit (3) determining the therapeutic potential of drugs in motility disorders. Pieces of intestines can be easily obtained from smaller animals. For assay purposes, guinea pig ileum is chosen because it yields steady base-line, for studying the effects of drugs on pendular movements (Finkleman method), rabbit jejunum is used. Effect of drugs on peristalsis can be studied by setting up guinea pig ileum preparation by the method of Trendelenburg. The functional components of the isolated intestines are terminal sympathetic and parasympathetic synapses as well as parasympathetic ganglionic synapse. Stimulation of sympathetic nerves inhibits peristaltic movements, while parasympathetic stimulation increases movement. Most experiments involve the investigation of drug action on the contractions of the longitudinal muscle. A simple method was developed to generate spatio-temporal maps of patterns of movement in the isolated guinea-pig ileum. A new approach was developed for a quantitative and comprehensive evaluation of the force-time curve of guinea pig gut contractions. Isolated colon smooth muscle cells can be used to assess the receptor binding studies.

KEYWORDS: Jejunum, Ileum, Intestinal motility, Longitudinal muscle