Document Type
Article
Abstract
Aquaporins (AQPs) are critical for transmembrane water transport in response to osmotic gradients, but their gating and regulatory mechanisms remain poorly understood. A central challenge is the lack of methods to measure water flow across AQPs from individual cells with the spatiotemporal resolution and sensitivity equivalent to patch-clamp recordings of ion fluxes—a limitation stemming from the electrically silent nature of water flow. Here, we present a novel optical technique—Flow-Induced Fluorescence Increase Velocimetry (FIFIV) based on Laser-Induced Fluorescence Photobleaching Anemometry (LIFPA)—that enables direct, real-time monitoring of cytoplasmic flow induced by transmembrane water transport under osmotic pressure gradients. Using small molecular fluorescent dyes to label cytoplasm in single adherent MDA-MB-231 breast cancer cells, we show detection of instantaneous extremely low transmembrane water flow signals on the order of 1 μm/s following localized hypotonic stimulation. This approach circumvents the limitations of traditional volume-based osmotic permeability assays, achieving single-cell sensitivity and temporal resolution comparable to electrophysiological measurements of ion flux. FIFIV potentially provides a new optical approach for probing transmembrane water-flow–induced intracellular dynamics, and a foundation for future investigations of AQP regulation and gating mechanisms in physiopathological studies and drug discovery.
Digital Object Identifier (DOI)
Publication Info
Published in The Journal of Membrane Biology, Volume 259, Issue 8, 2026.
Rights
© The Author(s) 2026 This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
APA Citation
Jiang, H., Jongkhumkrong, J., Chao, Y. J., Wang, Q., & Wang, G. (2026). Rapid Single-cell Measurement of Transient Transmembrane Water Flow under Osmotic Gradient. The Journal of Membrane Biology, 259, 8.https://doi.org/10.1007/s00232-026-00375-6