The role of thoracic duct lymph in gastrin transport and gastric secretion

Abstract

SUMMARY The effect of thoracic lymph diversion on gastric secretion has been studied in dogs. In addition, the concentration of gastrin in thoracic duct lymph of nine dogs and two patients has been measured before and during antral stimulation with either food or acetylcholine. The secretory studies do not support the concept that there is a significant gastric secretagogue in thoracic duct lymph. The amount of gastrin carried in thoracic duct lymph as determined by radioimmunoassay is far less than that necessary to evoke a gastric secretory response.The routes by which gastrin travels between its major site of production, the gastric antrum, and its target organs, in particular the gastric fundus, have not been fully determined. The premise that most or all of the antral gastrin is carried in the portal venous system through the liver to the systemic circulation is supported by the studies of Jackson, Reeder, and Thompson (1972) in which high levels of gastrin have been measured in the antral venous drainage of dogs.Another possible channel for the transport of gastrin, the lymphatic system, has not been explored directly. Previous studies on the effect of interruption of flow of thoracic duct lymph on gastric secretion have given conflicting results. Evidence has been presented which suggests on the one hand that substances which inhibit gastric secretion are present in the lymph (Johnston and Code, 1960;Rudick, Gajewski, Pitts, Semb, Fletcher, Harkins, and Nyhus, 1965) and on the other hand that there are gastric secretagogues, perhaps gastrin, in the lymph (Johnston and Code, 1960;Kelly, Ikard, Nyhus, and Harkins, 1963;Rudick and Dreiling, 1967;Rudick, Fletcher, Dreiling, and Kark, 1968;Bondar, 1966 and1967).In the present study the concentrations of gastrin in thoracic duct lymph have been measured directly by radioimmunoassay during basal conditions and during strong antral stimulation, and the effect of external diversion of lymph on the output of gastric acid has been reexamined. Materials and MethodsFour groups of experiments were performed. Fourteen healthy alert adult mongrel dogs weighing 17-22 kg were used. GROUP 1In five dogs denervated gastric (Heidenhain) fundic pouches (HP) and antral fistulas were constructed and the dogs were allowed to recover for a period of at least four weeks. The dogs were then anaesthetized, a right thoracotomy was performed and the thoracic duct divided just above the diaphragm. The caudal end of the duct was cannulated with a polyvinyl tube that was brought through the chest wall, threaded subcutaneously for a distance of 10 cm, reintroduced into the thoracic cavity, and then tied into the cephalic end of the thoracic duct. The catheter was positioned at a subcutaneous site that would permit easy access in the conscious dog, using local anaesthesia, for diversion of lymph from the caudal thoracic duct to the exterior. Lymph flow in the thoracic duct could be restored by reconnecting the polyvinyl tubing.Tests were begun on the first postoperative day. The dogs were p...

Lymph, Pancreatic and Gastrointestinal Hormones in Response to Feeding in the Conscious Pig

“…It is notable that several of the gut hormones affect mesenteric blood flow and may thereby influence lymph flow [8,9,19,24,28], An increase in lymph flow has been demonstrated in response to secre tin, CCK and glucagon although a physiolog ical role for these peptides in control of blood flow has not been established [8,9,24,28], There have been few previous studies on the transport of the gastrointestinal hor mones in lymph. Several workers have re ported the presence of gastrin in lymph [5,18]. Basal gastrin concentrations were similar to those found in the present study but no significant postprandial rise of lymph gastrin concentrations was reported [5,18].…”

“…Several workers have re ported the presence of gastrin in lymph [5,18]. Basal gastrin concentrations were similar to those found in the present study but no significant postprandial rise of lymph gastrin concentrations was reported [5,18]. It should be emphasised that these early studies em ployed a diversion of the thoracic duct lymph which is derived from a wide area and in cludes a hepatic contribution.…”

“…Several observations [14,25,29,30] sug gest an important role for lymph in the trans port of gastrin, but others [5,11,18] indicate that the contribution is negligible. It should be emphasized that most of these studies have been made on lymph diverted from tho racic duct, which drains from a wide area including the liver [2], Similar studies in relation to cholecystokinin [27] and insulin [20][21][22] also yield con flicting results [2].…”

“…Several relevant studies have been carried out [5,12,14,17,18], but the evidence for lymphatic participation in the mediation of the humoral phase of digestion is conflicting [2]. Several observations [14,25,29,30] sug gest an important role for lymph in the trans port of gastrin, but others [5,11,18] indicate that the contribution is negligible.…”