2005 Abstracts: Intra-Abdominal Inflammation Stimulates Rat Intestinal Glutamine Absorption
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Intra-Abdominal Inflammation Stimulates Rat Intestinal Glutamine Absorption
Haroon Choudry, Wiley Souba, QengHe Meng, Anne Karinch, ChengMao Lin, Ming Pan, Penn State Hershey Medical Center, Hershey, PA
Background: Glutamine is an essential nutrient in maintaining intestinal integrity and reducing systemic catabolism in catabolic states. Intestinal mucosal glutamine absorption is the initial step for glutamine to enter the host. However, regulatory mechanisms involved in intestinal glutamine absorption, in stress states, remain unclear. The purpose of this in vivo study was to investigate effects of intra-abdominal inflammation on rat intestinal glutamine transport.
Methods: Adult male Sprague-Dawley rats underwent laparotomy with intraperitoneal implantation of sterilized fecal-pellet (Inflammation) or sham laparotomy alone (Control). Rats remained NPO post-surgery and jejunum was harvested at various post-surgery time-points. Radiolabeled [3H]-Glutamine (1-10mM) transport activity was measured using jejunal brush-border membrane vesicles (BBMV). Jejunal glutamine transporter ATB° mRNA and protein levels were assayed using Real Time PCR and Western Blot techniques, respectively. Data was analyzed using t-test with significance set at p<0.05. Handling and care of animals conformed to standard guiding principles. Results: Sterile inflammation resulted in a 2-fold increase in glutamine transport activity 12 hours following induction of intraperitoneal inflammation (Inflammation 18.4 ± 3.8 pmole/mg protein/10 sec vs. Control 8.6 ± 1.2 pmole/mg protein/10 sec, n=9, p<0.01). The stimulation was first observed at 6 hours post-surgery, peaked at 12 hours and there was minimal change five days post-surgery. Sterile inflammation increased the glutamine transporter ATB°maximal transport capacity (Vmax, Inflammation 910 ± 260 pmole/mg protein/10 sec vs. Control 530 ± 150 pmole/mg protein/10 sec, n=6, p<0.05) without changing the transport affinity (Km, Inflammation 176 ± 39 mM vs. Control 158 ± 33 mM, n=6, p=NS). Sterile inflammation caused a 3.5-fold increase in ATB0 mRNA levels (Inflammation 3.58 ± 2.24 vs. Control 1 ± 0.28, n=9, p<0.002) and a 2-fold increase in intestinal brush-border membrane glutamine transporter ATB0 protein levels (Inflammation 2.3 ± 1.16 vs. Control 1 ± 0.2, n=9, p<0.001). Conclusions: Intra-abdominal sterile inflammation stimulates rat intestinal mucosal glutamine transport activity, as well as transporter mRNA and protein levels that leads to an increase in functional transporter units. Increased intestinal glutamine absorption may help maintain glutamine homeostasis in stress states.
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