Ussing chamber experiments for distension evoked secretion in human colon

Study Purpose: Based on different animal models, a correlation between motility and secretion in the gastrointestinal tract has been established previously. Within the aim of this work, new insights into the distension- and pressure-induced secretion were gained by means of the voltage clamp method in the Ussing chamber. For this purpose, experiments were performed for the first time on human intestinal resections.

Data Collection: This dataset contains the results of Ussing chamber experiments for distension-evoked secretion in mucosa/submucosa preparations from human colon. Distension volume and pressure were precisely controlled by a custom injection system, and we used a pharmacological approach to identify ion channels and pathways that are involved in the secretory responses.

Primary Conclusion: It was shown that distension elicited a secretory response in human intestinal samples; chloride and bicarbonate anions mediate the distension-induced secretion evident by the significant reduction of distension-induced secretion in chloride- and chloride/bicarbonate-free experimental buffers. Therefore, the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) plays a major role in these processes in humans. Reduction of distension by increasing compression via incorporation of filters showed that the pressure-induced secretory response is mediated primarily by distension rather than compression. In addition, higher pressures of 2-60 mmHg also elicited higher secretory responses in human tissues. In four of five human large-bowel regions tested, there was a lower distension-induced secretion response with mucosal stimulation compared to serosal stimulation. Because the cyclooxygenase inhibitor piroxicam significantly reduced the distension-induced secretion response, an important role of prostaglandins in distension-induced secretion was revealed. Subsequent application of tetrodotoxin revealed a minor but significant nervous component. The ꙍ-conotoxin GVIA-sensitivity demonstrated the importance of mechanosensitive synapses in mediating distension-induced secretion in the human colon. Thus, the results of this work demonstrate that distension-induced secretion in humans is mediated by both prostaglandins and nerves.

Curator's Notes

Experimental Design: Large intestine human tissue samples were obtained from patients undergoing surgery at the Medical Clinics in Freising, Erding and Rechts der Isar (Munich, Germany). Samples were taken from macroscopically unaffected areas and were immediately inspected by a pathologist and transported to the laboratory for dissection of mucosa/submucosa preparations. All procedures were performed in accordance with the Declaration of Helsinki (Ethical Principles for Medical Research Involving Human Subjects) and were approved by the ethics committee of the Technische Universität München (5242/11). All patients gave written informed consent. Colonic mucosa-submucosa preparations were cut into pieces of 1cm² or 0.5cm² and mounted in the Ussing chamber holders( https://doi.org/10.26275/4QVR-KWZQ)(serosal area 1.08 cm2). In this system, intestinal tissues are fixed between the two halves of a chamber, forming a mucosal and a serosal compartment that are filled with an appropriate buffer solution. The movement of ions across the intestinal epithelium produces a potential difference (PD), which is set to 0 mV under the applied short circuit (Isc) conditions, using a voltage clamp device (EC-285, Warner Instruments). An electrical field stimulation (EFS; 10 s train pulse with 1 ms single pulse duration at 20 V (human tissue) was applied by a constant voltage stimulator (Grass SD9 and SD48; Astro-Med Inc., West Warwick, RI, USA) connected to platinum electrodes in order to evoke a neuronal mediated increase in Isc revealing tissue viability prior to pressure application. Only tissues exhibiting an EFS-induced increase in Isc suggesting active transepithelial ion secretion were used for further experiments. 80% of the human tissue responded to the EFS.

Completeness: This dataset is complete.

Subjects & Samples: Samples from 95 human patients, collected from both females (n=50) and males (n=45), were used in this dataset.

Primary vs derivative data: Primary data is organized in folders by the subject ID and then sample ID and consists of tabular data showing secretion response of the tissue measured in µA/cm^2 and pressure in mmHg, stimulation of all channels are shown in .xlsx file format. Comments columns show the channel-specific stimulation list. There is no derivative data folder.