A self-referencing Cl--selective microelectrode (Cl- SrE) was developed and used to detect changes in the direction and magnitude of the Cl- flux (J(Cl)) from the apical region of cultured foetal distal lung epithelial cells (FDLEs) as a function of external Cl- concentration ([Cl-]e) and in response to pharmacological challenges. The technique, which is similar to that developed for other ion-selective microelectrodes, centres on the oscillation of a Cl--selective microelectrode between known points, micrometres apart, orthogonal to the plasma membrane. Application of the Fick principle to the differential voltage obtained per excursion amplitude (the referenced signal) yields the Cl- flux (pmol × cm(−2) × s(−1)). A Cl- effusion gradient was used to confirm that empirical measurements of J(Cl) using the Cl- SrE were statistically similar to predicted flux values calculated from the fall in [Cl-] with distance from the tip of the effusion source. Apical J(Cl) was then measured as a function of [Cl-]e from polarised FDLE cultures grown on permeable supports. At [Cl-]e<50 mmol × l(−1), an apical-to-basolateral (inward) flux, maximal at 400 pmol × cm(−2) × s(−1), was observed; this reverted to a continuous basolateral-to-apical (outward) flux of 203 pmol × cm(−2) × s(−1) at [Cl]e>100 mmol × l(−1). At [Cl-]e>100 mmol × l(−1), isoproterenol (basolaterally applied, 10 micromol × l(−1)) activated a Cl- influx of 561 pmol × cm(−2) × s(−1), whereas UTP (apically applied, 100 micromol × l(−1)) stimulated a Cl- efflux of 300 pmol × cm(−2) × s(−1). In all cases, 50–70 % of J(Cl) was abolished by Cl- channel blockade using 10 micromol × l(−1) diphenylamine-2-carboxylic acid (DPC) or 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB). We conclude that the Cl- SrE resolves a Cl- gradient in the microenvironment of the apical region of lung epithelia that varies in both direction and magnitude as a function of external [Cl-]e and in response to Cl- channel blockade and to beta2 adrenoreceptor and P2Y receptor agonists.
The Integrative Biology of the Heart
We are pleased to welcome submissions to be considered for our upcoming special issue: The Integrative Biology of the Heart, guest edited by William Joyce and Holly Shiels. This issue will consider the biology of the heart at all levels of organisation, across animal groups and scientific fields.
JEB@100: an interview with Monitoring Editor John Terblanche
John Terblanche reveals how he narrowly avoided becoming a sports scientist and why he thinks phenotypic plasticity is the big question currently facing comparative physiologists. Find out more about the series on our Interviews page.
Vision 2024: Building Bridges in Visual Ecology
Early-career researchers can apply for funded places at our Vision 2024: Building Bridges in Visual Ecology. The event is organised by Eleanor Caves, Sonke Johnsen and Lorain Schweikert and being held at Buxted park 10-13 June 2023. Deadline 1 December 2023.
Reconciling the variability in the biological response of marine invertebrates to climate change
Drawing on work in reef-building corals, Zoe Dellaert and Hollie Putnam provide historical context to some of the long-standing challenges in global change biology that constrain our capacity for eco-evolutionary forecasting, as well as considering unresolved questions and future research approaches. Read the full Centenary Review Article here.
Sipping takes no effort for hovering hawkmoths
Hovering takes the most effort so how much energy does sipping require when hawkmoths hover? Next to nothing, apparently. Alexandre Palaoro & colleagues have discovered that the insects’ proboscises are incredibly wettable, drawing nectar along the length with no effort, giving them a free drink on the wing.
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