Water and osmolyte homeostasis is an essential biological function. Remarkably devoid of aquaporin (i.e., water channel protein) expression, the stratumcorneumavoids a substantial transepidermal water loss, compulsory for the adaptation to terrestrial life. In spite of its heterogeneity, the stratum corneumexhibits a homogeneous water transport, whereas highly osmotic endogenous materials control its water-holding capacity and skin’s physical properties (e.g., stiffness, firmness, flexibility) under various conditions. However, the contingent interplay between water homeostasis of the stratum corneumand an exogenous osmotic stress has been not reported, although constituting a cornerstone of skin physiology. Here, we show that an osmotic shock reinforces the endogenous stratum corneumosmolality proportionally to the osmotic pressure exerted against it and, therefore, reduces the magnitude of outward water transfer and net evaporation. The strengthening of endogenous osmolality enhanced the water-holding capacity of the stratum corneum with respect to chemical potentials. This property was found for organic osmolytes, but questioned for mineral electrolytes characterized by minimal stratum corneumpermeability. Besides, straightforward experiments performed using a built-in house osmometer, a so-called ‘corneosmometer’, have confirmed water transfer through the stratum corneumsubmitted to a gradient of osmotic pressure. Thus, the ambivalent function of the stratum corneum, which firstly behaves as an ideal osmometer and secondly adapts its own osmolality to an exogenous gradient of osmotic pressure, has been clearly demonstrated. This duality influences the water-holding capacity of the stratum corneum, by regulating the water transfer proportionally to an initial osmotic stress, and, finally, conditions the further capacity of the stratum corneumto facilitate or impede skin hydration.

This content is only available via PDF.
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.