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Absorption of glucose at concentrations exceeding the capacity of sodium glucose co-transporter 1 (SGLT1) is attributed to the recruitment of GLUT2 at the apical membrane of enterocytes in vivo. Protein kinase C (PKC) has been implicated in this process in cell culture and in vitro. HYPOTHESIS: Activating and inhibiting protein kinase C (PKC) will increase and decrease, respectively, GLUT2-mediated glucose absorption via a mechanism dependent on the microtubular cytoskeleton. AIM: To explore the role of PKC in activating GLUT2-mediated glucose absorption. METHODS: Isosmolar glucose-containing solutions were perfused through isolated, 30-cm segments of jejunum in anesthetized rats. Carrier-mediated glucose uptake was measured in 10 mM and 100 mM glucose solutions (n=6 rats, each) with and without 10 µM chelerythrine (PKC inhibitor), 200 nM PMA (PKC activator), and 10 µM nocodazole (microtubule disruptor). Carrier-mediated absorption of glucose was calculated by the difference in amount infused minus the amount recovered after subtracting passive absorption (³H-L-glucose) and expressed as mean±SEM; n=6. After ending the experiment, the mucosa was harvested rapidly in 4°C temperature; brush border membranes were isolated and subjected to Western blot analysis. RESULTS: Inhibition of PKC with chelerythrine chloride at the 10 and 100 mM glucose concentrations resulted in a small decrease in carrier-mediated absorption from 2.3±0.2 to 1.9±0.3 µmol/min/30-cm intestine (p<0.0001) and 10.8±1.8 to 9.0±1.7 µmol/min, respectively. PMA (PKC stimulant) also decreased absorption at the 10 and 100 mM perfusates (1.9±0.1 to 1.6±0.2; p<0.003 and 13.7±1.2 to 11.6±1.5, respectively). Nocodazole (microtubular disruption) decreased carrier-mediated uptake at 10 mM glucose from 2.1±0.2 to 1.7±0.2 (p<0.0008) and from 13.5±1.6 to 12.9±1.5 at 100 mM glucose. No significant changes were observed at the 100 mM glucose perfusate with all three pharmacologic agents. Western blots of isolated brush border membranes showed no difference in GLUT2 levels at the 10 and 100 mM glucose concentrations. CONCLUSIONS: Activation and/or inhibition of protein kinase C and disruption of microtubular architecture had minimal effect at the concentration of luminal glucose when GLUT2 should be maximally translocated. Other intracellular pathways (such as activation of sweet taste receptors or voltage-gated Ca2⁺ channels) may be responsible for increasing GLUT2 activity at the apical membrane. (Support: NIH Grant DK39337 [MGS]).