Resveratrol Inhibits Porcine Intestinal Glucose and Alanine Transport: Potential Roles of Na+/K+-ATPase Activity, Protein Kinase A, AMP-Activated Protein Kinase and the Association of Selected Nutrient Transport Proteins with Detergent Resistant Membranes

Abstract

Background: Beneficial effects of Resveratrol (RSV) have been demonstrated, including effects on transporters and channels. However, little is known about how RSV influences intestinal transport. The aim of this study was to further characterize the effects of RSV on intestinal transport and the respective mechanisms. Methods: Porcine jejunum and ileum were incubated with RSV (300 µM, 30 min) in Ussing chambers (functional studies) and tissue bathes (detection of protein expression, phosphorylation, association with detergent resistant membranes (DRMs)). Results: RSV reduced alanine and glucose-induced short circuit currents (ΔIsc) and influenced forskolin-induced ΔIsc. The phosphorylation of sodium–glucose-linked transporter 1 (SGLT1), AMP-activated protein kinase (AMPK), protein kinase A substrates (PKA-S) and liver kinase B1 (LKB1) increased but a causative relation to the inhibitory effects could not directly be established. The DRM association of SGLT1, peptide transporter 1 (PEPT1) and (phosphorylated) Na+/H+-exchanger 3 (NHE3) did not change. Conclusion: RSV influences the intestinal transport of glucose, alanine and chloride and is likely to affect other transport processes. As the effects of protein kinase activation vary between the intestinal localizations, it would appear that increasing cyclic adenosine monophosphate (cAMP) levels are part of the mechanism. Nonetheless, the physiological responses depend on cell type-specific structures.

Calcium-induced chloride secretion is decreased by Resveratrol in ileal porcine tissue

“…3a, I sc was increased by RSV (p = 0.029) what validates the results from our previous study [22]. Since this increase was absent under Cl − -free conditions (p = 0.0001), this part of the study confirms, that the RSV-mediated increase is caused by Cl − secretion as it was speculated.…”

“…3b, RSV decreased the glucose-induced ΔI sc (p = 0.002), what is already known from our previous studies [22, 25]. Additionally, this part of the study may give some new indications that RSV may affect Ca 2+ -induced Cl − secretion since the glucose-induced I sc for ctrl/Cl − -free chambers was decreased compared to ctrl/Cl − chambers (p = 0.014).…”

“…This could not finally be elucidated from the present data but it seems reasonable to assume that a cAMP-mediated activation of CFTR may be the reason for the RSV-induced Cl − secretion as it was the case in the murine jejunum [19]. If the observed Cl − secretion would be due to CFTR activation, this might explain why RSV had no effect on ileal forskolin-induced I sc in our previous study [22], when assuming that CFTR is working at its maximal capacity after activation by RSV.…”

“…After an equilibration period with chloride-containing or chloride-free buffer solutions, RSV (Sigma-Aldrich, 300 µM) or ethanol (control, 20 µl/10 ml) were added to the mucosal compartment. After 30 min, glucose (10 mM mucosal) was applied in order to induce Na + -coupled glucose transport which is known to be inhibited by RSV [22, 25]. After another 10 min, carbachol (10 µM serosal, Sigma-Aldrich) was added to stimulate Ca 2+ -induced Cl − secretion (ΔI sc carbachol 1) [3].…”

“…In a recent study [22], we investigated the effects of RSV on intestinal transport using porcine jejunal and ileal samples in Ussing chamber experiments. After incubation with RSV, porcine jejunal tissues showed a decreased I sc while the ileum showed an increased I sc .…”