Phloridzin inhibits high K⁺-induced contraction via the inhibition of sodium: glucose cotransporter 1 in rat ileum

Abstract

Recent studies have shown that phloridzin, an inhibitor of sodium–glucose cotransporter (SGLT), strongly decreases high K+-induced contraction in phasic muscle, such as tenia coli, but slightly affects tonic muscle, such as trachea . In this study, we examined the inhibitory mechanism of phloridzin on high K+-induced muscle contraction in rat ileum, a phasic muscle. Phloridzin inhibited the high K+-induced contraction in the ileum and the aorta, and the relaxing effect of phloridzin at 1 mM in the ileum was approximately five-fold more potent than that in the aorta. The expression of SGLT1 mRNA in the ileum was higher than that of the aorta. Phloridzin significantly inhibited NADH/NAD ratio and phosphocreatine (PCr) content in the ileum; however, application of pyruvate recovered the inhibition of contraction and PCr content, but had no effect on ratio of NADH/NAD. High K+ increased 2-(N (7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino)-2-deoxyglucose (2-NBDG) uptake in ileal smooth muscle cells, and phloridzin inhibited the increase in a concentration-dependent manner. These results suggest that phloridzin inhibits high K+-induced contraction because of the inhibition of energy metabolism via the inhibition of SGLT1.

The Bioavailability, Extraction, Biosynthesis and Distribution of Natural Dihydrochalcone: Phloridzin

“…Wang et al [ 103 ] found that extracts from the fruits of Malus baccata contained phloridzin, and the extracts had radioprotective and immunomodulatory activities. Kanda et al [ 104 ] found that phloridzin strongly decreased high K + -induced contraction in phasic muscle (tenia coli), but slightly affected tonic muscle (trachea) because of the inhibition of energy metabolism via SGLT1. Li et al [ 105 ] found that phloridzin increased NO output, suppressed SGLT1 and SGLT2 expression, and promoted the consumption of glucose, which ameliorated endothelial dysfunction by the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/endothelial nitric oxide synthase (eNOS) signaling pathway in palmitic acid-induced human umbilical vein endothelial cells.…”