Investigation of a potential electrogenic transport-system for <i>myo</i>-inositol in the small intestine of laying hens
Creators: name: Röhm, Katrin
name: Gonzalez-Uarquin, Fernando
name: Harmel, Robert K.
name: Trung, Minh Nguyen
name: Diener, Martin
name: Fiedler, Dorothea
name: Huber, Korinna
name: Seifert, Jana
Publisher: name: Taylor & Francis
Year: 2021
Subjects: subject: Biophysics
subject: Biochemistry
subject: Medicine
subject: Microbiology
subject: FOS: Biological sciences
subject: Cell Biology
subject: Genetics
subject: Molecular Biology
subject: Physiology
subject: Pharmacology
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: 69999 Biological Sciences not elsewhere classified
subject: Developmental Biology
subject: Cancer
subject: 110309 Infectious Diseases
subject: FOS: Health sciences

description: <i>Myo</i>-inositol (MI) is an essential metabolite for cell function in animals and humans. The aim of this study was to characterise the transport mechanism of MI in the small intestine of laying hens as there is a lack of knowledge about the MI uptake mechanisms. The hypothesized secondary active, cation coupled transport of MI was assessed by electrophysiological measurements with Ussing chambers, and was compared to the electrophysiology of glucose transport.Twenty-six laying hens were used. The potential ion-dependent transport was tested in tissue of the small intestine. Barrier function of the tissue was shown by determining the transepithelial resistance. During the experiments, mucosal and serosal buffer was sampled to measure time-dependent changes in MI concentrations. Samples from eight hens were further used for Western blot analyses of the jejunal apical membranes.Active MI transport, indicated by changes in the short circuit current after MI addition, could not be demonstrated in the Ussing chambers experiments. MI was further not detectable in the serosal buffer, nor in the lysates of mucosal tissue cytoplasm nor lipids. Thus, there was no evidence for a MI transport or absorption. However, Western blot analyses of the jejunal apical membrane revealed signals indicated the expression of the MI transport proteins SMIT-1 and SMIT-2.In conclusion, the MI transport process in the chicken intestine is more complex than it was presumed and is probably influenced by still unknown regulations or metabolic processes. <i>Myo</i>-inositol (MI) is an essential metabolite for cell function in animals and humans. The aim of this study was to characterise the transport mechanism of MI in the small intestine of laying hens as there is a lack of knowledge about the MI uptake mechanisms. The hypothesized secondary active, cation coupled transport of MI was assessed by electrophysiological measurements with Ussing chambers, and was compared to the electrophysiology of glucose transport. Twenty-six laying hens were used. The potential ion-dependent transport was tested in tissue of the small intestine. Barrier function of the tissue was shown by determining the transepithelial resistance. During the experiments, mucosal and serosal buffer was sampled to measure time-dependent changes in MI concentrations. Samples from eight hens were further used for Western blot analyses of the jejunal apical membranes. Active MI transport, indicated by changes in the short circuit current after MI addition, could not be demonstrated in the Ussing chambers experiments. MI was further not detectable in the serosal buffer, nor in the lysates of mucosal tissue cytoplasm nor lipids. Thus, there was no evidence for a MI transport or absorption. However, Western blot analyses of the jejunal apical membrane revealed signals indicated the expression of the MI transport proteins SMIT-1 and SMIT-2. In conclusion, the MI transport process in the chicken intestine is more complex than it was presumed and is probably influenced by still unknown regulations or metabolic processes.