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Aim: To examine the likelihood of mortality or rehospitalization following acute coronary syndrome with glyburide versus gliclazide use in adults with type 2 diabetes undergoing cardiac catheterization. Research Design and Methods: This retrospective cohort study used clinical data linked with administrative health data from Alberta, Canada between April 2008 and March 2021. Three methods were used to define exposure to glyburide and gliclazide in the year before catheterization. Multivariable logistic regression was used to compare the likelihood of a composite outcome of 1‐year mortality or rehospitalization with use of glyburide versus use of gliclazide. Results: A total of 11 140 individuals with type 2 diabetes had a cardiac catheterization for acute coronary syndrome. Their mean age was 66 years and 31% were female. In the year before catheterization, 5% used glyburide and 19% used gliclazide. Any glyburide or gliclazide exposure in the year before catheterization was associated with a similar likelihood of all‐cause mortality or rehospitalization (adjusted odds ratio [aOR] 1.14, 95% confidence interval [CI] 0.93–1.41; p = 0.20). However, current glyburide exposure (aOR 1.37, 95% CI 1.06–1.79; p = 0.018) and long exposure to glyburide (aOR 1.37, 95% CI 1.03–1.83; p = 0.030) were associated with a higher likelihood of the composite outcome compared to current and long exposure to gliclazide, respectively. Conclusions: Current and long exposure to glyburide was associated with a greater likelihood of mortality or rehospitalization following cardiac catheterization for acute coronary syndrome, when compared to similar gliclazide exposure definitions. This study adds further evidence of the need to avoid using glyburide if a sulphonylurea is required for type 2 diabetes management. [ABSTRACT FROM AUTHOR]

Autosomal dominant polycystic kidney disease is caused by mutations in the membrane receptor PKD1 or the cation channel PKD2. TACAN (also termed TMEM120A), recently reported as an ion channel in neurons for mechanosensing and pain sensing, is also distributed in diverse non‐neuronal tissues, such as kidney, heart and intestine, suggesting its involvement in other functions. In this study, we found that TACAN is in a complex with PKD2 in native renal cell lines. Using the two‐electrode voltage clamp in Xenopus oocytes, we found that TACAN inhibits the channel activity of PKD2 gain‐of‐function mutant F604P. TACAN fragments containing the first and last transmembrane domains interacted with the PKD2 C‐ and N‐terminal fragments, respectively. The TACAN N‐terminus acted as a blocking peptide, and TACAN inhibited the function of PKD2 by the binding of PKD2 with TACAN. By patch clamping in mammalian cells, we found that TACAN inhibits both the single‐channel conductance and the open probability of PKD2 and mutant F604P. PKD2 co‐expressed with TACAN, but not PKD2 alone, exhibited pressure sensitivity. Furthermore, we found that TACAN aggravates PKD2‐dependent tail curvature and pronephric cysts in larval zebrafish. In summary, this study revealed that TACAN acts as a PKD2 inhibitor and mediates mechanosensitivity of the PKD2–TACAN channel complex. Key points: TACAN inhibits the function of PKD2 in vitro and in vivo.TACAN N‐terminal S1‐containing fragment T160X interacts with the PKD2 C‐terminal fragment N580–L700, and its C‐terminal S6‐containing fragment L296–D343 interacts with the PKD2 N‐terminal A594X.TACAN inhibits the function of the PKD2 channel by physical interaction.The complex of PKD2 with TACAN, but not PKD2 alone, confers mechanosensitivity. [ABSTRACT FROM AUTHOR]

Xenopus laevis oocytes are a useful heterologous expression system for expressing glucose transporters (GLUTs) and examining their functions. In this chapter, we provide a detailed protocol on oocyte extraction and preparation for GLUT9 protein expression. Furthermore, we describe the determination of GLUT9 overexpression level by biotinylation and Western blotting analysis. Finally, we also describe how GLUT9-expressing oocytes can be used to measure urate kinetics by radioisotopes as well as two-microelectrode voltage clamping techniques.

Transient receptor potential (TRP) polycystin 2 and 3 (TRPP2 and 3) are homologous members of the TRP superfamily of cation channels but have different physiological functions. TRPP2 is part of a flow sensor, and is defective in autosomal dominant polycystic kidney disease and implicated in left-right asymmetry development. TRPP3 is reported to implicate in sour tasting in bipolar cells of taste buds of the tongue and in the regulation of pH-sensitive action potential in neurons surrounding the central canal of spinal cord. TRPP3 is present in both excitable and non-excitable cells in various tissues, such as retina, brain, heart, testis, and kidney, but its common and cell type-specific functional characteristics remain largely unknown. In this study, we investigated physical and functional interactions between TRPP3 and alpha-actinin, an actin-bundling protein known to regulate several types of ion channels. We employed planer lipid bilayer electrophysiology system to study the function of TRPP3 channel that was affinity-purified from Madin-Darby canine kidney cells. Upon reconstitution in bilayer, TRPP3 exhibited cation channel activities that were substantially augmented by alpha-actinin. The TRPP3-alpha-actinin association was documented by co-immunoprecipitation using native cells and tissues, yeast two-hybrid, and in vitro binding assays. Further, TRPP3 was abundantly present in mouse brain where it associates with alpha-actinin-2. Taken together, alpha-actinin not only attaches TRPP3 to the cytoskeleton but also up-regulates TRPP3 channel function. It remains to be determined whether the TRPP3-alpha-actinin interaction is relevant to acid sensing and other functions in neuronal and non-neuronal cells.