Although the target and emphasis of all the BRC core developments is the single mammalian cell, utilization of the self-referencing sensor technologies developed by the BRC showed that they operate easily in larger bulk domains as well.  The chemical profiles surrounding tissues and sheets of epithelial and endothelial structures are good examples.  Several of our collaborative ventures, such as a study on the male reproductive system of the rat (vas deferens and epidydimus), have taken advantage of this capability with productive results.

The diameter of the vas deferens tube is small- approximately 100µm- but, when slit open and folded back, the surface can be scanned by a SERIS (Self-Referencing Ion Selective) electrode tailored for hydrogen ion detection. Hot spots are detected.¹³ With such a defined signal profile, pharmacological studies allow the examination of the source, its underlying biochemical pathway, as well as the transport and incorporation of transporters into the epithelial structure.¹

Taking an epithelial tissue and flattening it under an upright microscope fitted for differential interference contrast microscopy allows single cells within the surface architecture to be targeted by electrochemical microelectrodes operating in the self-referencing mode (see figure above).

Lung epithelial cells, where chloride ion movement participates in water transport, have also been studied.⁶

Endothelial structures can also be examined with ion selective microelectrodes operating in the self-referencing format. Small capillaries have been examined where a temperature dependent Cl^- efflux correlated with myogenic contraction.⁵ It should be noted, as it was in this and other studies, that this electrode design is difficult to use and its misuse by others has left spurious data in the literature. See reference 2 for a discussion.