A thermodynamically consistent approach to modelling epithelial solute and water transport in the proximal convoluted tubule

A thermodynamically consistent approach to modelling epithelial solute and water transport in the proximal convoluted tubule | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article A thermodynamically consistent approach to modelling epithelial solute and water transport in the proximal convoluted tubule Leyla Noroozbabaee, Jarrah M. Dowrick, Pablo J. Blanco, David P. Nickerson This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7848928/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Abstract This study presents a novel approach to modeling ion and fluid transport in the renal nephron’sproximal convoluted tubule (PCT) using bond graph framework. Bond graphs provide a robust framework for analyzing complex systems by representing thermodynamic processes within an extended circuit-theoretic approach, enabling the explicit depiction of multi-domain energy exchange. Applications of bond graphs to physiological processes have primarily focused on solute transport, whereas our work distinguishes itself by also incorporating solvent dynamics and their interplay with solute transport, offering a more complete representation of the key physiological processes within the PCT. Leveraging the modular nature of bond graphs, we first defined resistive modules representing membranes and capacitive modules representing solution-filled compartments, before coupling them together using circuit theory. Critically, our novel implementation extends beyond previous bond graph models by explicitly representing volumetric flow as a distinct variable within capacitive modules. Indoing so, our model enables the consideration of mechanotransduction effects, where changes in fluid volume can influence membrane transporter activity, a crucial aspect of PCT function. Our bond graph model of the PCT (BG-PCT) comprises four fluid compartments bounded by five distinct membranes. The BG-PCT considers five chemical species ( Na+, K+, Cl−, HCO3−, and glucose) and six key membrane transporters distributed across the different membranes. Each structural subsystem comprises elementary thermodynamic processes, including dissipation, free-energy change, and power flow. This study demonstrates the advantages of bond graph modeling, particularly in its capacity to couple electrical, chemical, and hydraulic energy domains and its intrinsic modularity, which enables future extensibility. The BG-PCT offers a robust platform for in silico research of epithelial transport dynamics and is available on GitHub under an open-source license to ensure accessibility, reproducibility, and reusability for future research. bond-graph modeling kidney proximal convoluted tubule (PCT) solute transport water transport Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 19 Jan, 2026 Reviews received at journal 06 Jan, 2026 Reviewers agreed at journal 29 Dec, 2025 Reviews received at journal 22 Dec, 2025 Reviewers agreed at journal 01 Dec, 2025 Reviewers invited by journal 14 Nov, 2025 Editor assigned by journal 01 Nov, 2025 Submission checks completed at journal 28 Oct, 2025 First submitted to journal 13 Oct, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7848928","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":550051805,"identity":"1dbf152a-3cfd-4384-bb85-c13ca678ce3d","order_by":0,"name":"Leyla Noroozbabaee","email":"data:image/png;base64,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","orcid":"","institution":"Maastricht University","correspondingAuthor":true,"prefix":"","firstName":"Leyla","middleName":"","lastName":"Noroozbabaee","suffix":""},{"id":550051807,"identity":"89670917-e887-44bf-8621-f83ac9f3af98","order_by":1,"name":"Jarrah M. 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