A new animal model for intestinal lymph sampling for a new look at intestinal physiology

Abstract

Standard procedures for intestinal lymph collection involve continuous, quantitative sampling of lymph fluid and anesthetized or restrained animals that are often sacrificed after 48 h. We here describe a novel technique for the non-occlusive cannulation of the major mesenteric lymph duct in rats that allows for repetitive in-vivo sampling of intestinal lymph from unrestrained, awake and ad libitum-fed animals. The distinctive feature of this novel technique is that a 5–7 mm long piece of VialonTM tubing (OD/ID: 0.8/0.7 mm) with a small hole in its wall is first implanted into the mesenteric lymph duct for stabilization. The tapered tip (OD: 0.1 mm) of the catheter is then inserted into the hole of the tubing and fixed in place with a polyamid suture and a drop of tissue adhesive. In our hands, catheters implanted this way remain patent for up to 6 weeks after surgery. In one experiment we collected lymph from 6 adult rats prior to (0) and 15, 30, 45, 60, 75, 90,120, and 180 min (120 μl, each) after the onset of isocaloric (12 kcal) low fat (LF) or high fat (HF) test meals and measured active glucagon-like peptide-1 (GLP-1). Intestinal lymphatic GLP-1 concentration increased (p 5 pMol (0 min) to a peak of 30 ± 5 (mean ± SEM) or 21 ± 5 pMol at 15 (HF) or 30 min (LF) after meal onset and gradually returned to baseline levels by 180 min. With this new technique few animals suffice to generate physiologically relevant data for various aspects of gastrointestinal physiology that involve the lymphatic system.