Lymph, pancreatic and gastrointestinal hormones in response to feeding in the conscious pig

Concentrations of several gastrointestinal hormonal peptides were measured in lymph from the cisterna chyli and in arterial plasma; in healthy, conscious pigs during ingestion of a meal. Lymph concentrations of the pancreatic hormones insulin, glucagon and pancreatic polypeptide were small compared with plasma concentrations, although postprandial increments were significant. In contrast lymph concentrations of gastrin, cholecystokinin, motilin and gastric inhibitory peptide (GIP) from the foregut showed a more marked postprandial rise than the pancreatic hormones. Indeed the total integrated responses of these peptides in lymph reached about 50% of those seen in arterial plasma. It would appear unlikely that the lymphatics constitute an important transport mechanism for these regulatory peptides. However, lymph concentrations of hormones may reflect levels in interstitial fluid better than plasma and may be of value in assessing putative physiological actions within a target tissue.