title: Predicted consequences of diabetes and SGLT inhibition on transport and oxygen consumption along a rat nephron.
abstract: Diabetes increases the reabsorption of Na(+) (TNa) and glucose via the sodium-glucose cotransporter SGLT2 in the early proximal tubule (S1-S2 segments) of the renal cortex. SGLT2 inhibitors enhance glucose excretion and lower hyperglycemia in diabetes. We aimed to investigate how diabetes and SGLT2 inhibition affect TNa and sodium transport-dependent oxygen consumption [Formula: see text] along the whole nephron. To do so, we developed a mathematical model of water and solute transport from the Bowman space to the papillary tip of a superficial nephron of the rat kidney. Model simulations indicate that, in the nondiabetic kidney, acute and chronic SGLT2 inhibition enhances active TNa in all nephron segments, thereby raising [Formula: see text] by 5-12% in the cortex and medulla. Diabetes increases overall TNa and [Formula: see text] by ∼50 and 100%, mainly because it enhances glomerular filtration rate (GFR) and transport load. In diabetes, acute and chronic SGLT2 inhibition lowers [Formula: see text] in the cortex by ∼30%, due to GFR reduction that lowers proximal tubule active TNa, but raises [Formula: see text] in the medulla by ∼7%. In the medulla specifically, chronic SGLT2 inhibition is predicted to increase [Formula: see text] by 26% in late proximal tubules (S3 segments), by 2% in medullary thick ascending limbs (mTAL), and by 9 and 21% in outer and inner medullary collecting ducts (OMCD and IMCD), respectively. Additional blockade of SGLT1 in S3 segments enhances glucose excretion, reduces [Formula: see text] by 33% in S3 segments, and raises [Formula: see text] by <1% in mTAL, OMCD, and IMCD. In summary, the model predicts that SGLT2 blockade in diabetes lowers cortical [Formula: see text] and raises medullary [Formula: see text], particularly in S3 segments.
authors.affiliation: Department of Mathematics, Duke University, Durham, North Carolina; alayton@math.duke.edu.
authors.forename: Anita T
authors.initials: AT
authors.lastname: Layton
authors.affiliation: Departments of Medicine and Pharmacology, University of California San Diego, La Jolla, California, and San Diego Veterans Affairs Healthcare System, San Diego, California; and.
authors.forename: Volker
authors.initials: V
authors.lastname: Vallon
authors.affiliation: Sorbonne Universités, Université Pierre et Marie Curie, Université Paris 06, Université Paris Descartes, Sorbonne Paris Cité, Institut National de la Santé et de la Recherche Médicale UMRS 1138, Centre National de la Recherche Scientifique ERL 8228, Centre de Recherche des Cordeliers, Paris, France.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Edwards
mesh_terms: D000818:Animals; D003928:Diabetic Nephropathies / Q000378:metabolism*; D005919:Glomerular Filtration Rate / Q000502:physiology; D008954:Models, Biological; D009399:Nephrons / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D051381:Rats; D051297:Sodium-Glucose Transporter 2 / Q000378:metabolism*; D000077203:Sodium-Glucose Transporter 2 Inhibitors
chemical_list: D051297:Sodium-Glucose Transporter 2; D000077203:Sodium-Glucose Transporter 2 Inhibitors
keywords: diabetes; glucose; metabolism; sodium transport