In vitro and in situ experimental model for X‐ray microanalysis of intestinal epithelium

Abstract

Intestinal chloride (Cl) transport is disturbed in a number of diseases. X-ray microanalysis can be used to study the distribution of Cl and other ions in intestinal epithelial cells. In this study it was attempted to establish an experimental system that retains the in vivo elemental composition of intestinal epithelial cells. An in vitro system was set up in which a segment of rat intestine was mounted in a bath and perfused with different fluids. The chloride in the bath or in the perfusion fluid could be exchanged for gluconate or bromide to determine the direction of chloride fluxes. An in situ system was set up in which the animal was anesthetized and a segment of the intestine was perfused with different solutions. In the in vitro experiments the concentration of Na and Cl in the epithelial cells increased and that of K decreased. These changes occurred within the first 30 minutes of incubation. Uptake of chloride occurred mainly from the bath, as seen in experiments where bromide was used as a chloride analog. The concentration gradient between bath and tissue determined the extent of chloride uptake. Addition of glucose to the perfusion fluid and bath did not improve the results. In the in situ system, preservation of the intracellular ion composition was better. Acceptable results were obtained with perfusion with Krebs-Ringer's buffer without glucose for 30 minutes. In this case, the elemental content of the cell did not change appreciably during incubation. If glucose was added, the Na concentration increased in comparison to the control, both in crypt and villus cells. It is concluded that the intestinal epithelium is a sensitive system, very prone to disturbance of its homeostasis. However, the in situ system can be used in studies of agonist-induced ion transport.

Effects of dietary soybean meal and photoperiod cycle on osmoregulation following seawater exposure in Atlantic salmon smolts

“…This is conducive to the increased proportion of immunohistochemically detected proliferating cells lining the villous ridges of the inflamed intestine following SBM inclusion in diets for Atlantic salmon (Sanden et al , 2005 a ). Otherwise, intracellular element concentrations were not significantly altered by SBM in the diet and were similar to expected values reported in man (O’Loughlin et al , 1996) and other vertebrates such as mice (von Zglinicki & Roomans, 1993; Dragomir & Roomans, 2000), rat (Vanthanouvong et al , 2003), and guinea pig (Halm & Rick, 1992).…”

“…Apical and basal (in the crypt‐like areas) epithelial cells of the distal intestinal simple villous folds were analysed. The procedure used for microanalysis of the intestinal epithelium of rats, as described by Vanthanouvong et al (2003), was followed. The pieces of tissue previously frozen in chilled propane were sectioned at −30° C in a conventional cryostat adjusted to cut sections 16 μm thick.…”

Stratum Corneum Is an Effective Barrier to TiO₂ and ZnO Nanoparticle Percutaneous Absorption

“…Biopsies were mounted in mounting medium for microscopy (OCT TM compound), guaranteeing that they would not become fully immersed; thus, preventing the non-immersed part to suffer from unacceptable temperature gradients that would facilitate cell disruption and ion displacement [24,25] . Sections were obtained from the non-immersed portion of the tissue, and sectioning was performed from inside to outside to avoid tissue contamination with the sunscreen at the skin surface.…”

Investigation of the absorption mechanisms of baicalin and baicalein in rats

“…The perfusates were prepared as follows: first, the BG or B extract was dissolved in ethanol; then, tween80 was added as the solubilizer to improve the drugs' solubilities; finally, the mixture was diluted to the desired volume with artificial gastric juice11 (for gastric perfusate) or Krebs‐Ringer buffer12 (for intestinal perfusate). Besides, vitamin C (Vit C) was used as the antioxidant to improve the drugs' stabilities in the intestinal perfusate.…”