Published In

Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology

Document Type


Publication Date



Anura -- Physiology, Amphibians -- Physiology, Dehydration (Physiology), Hemoglobin, Oxygen -- Physiological transport, Blood cells


Anurans have an exceptional capacity for maintaining vascular volume compared with other groups of vertebrates. They can mobilize interstitial fluids via lymphatic return at rates that are ten-fold higher than mammals. This extraordinary capacity is the result of coordination of specialized skeletal muscles and pulmonary ventilation that vary volume and pressure of subcutaneous lymph sacs, thus moving lymph to dorsally located lymph hearts that return lymph to the vascular space. Variation in the capacity to mobilize lymph within anurans varies with the degree of terrestriality, development of skeletal muscles, lung volume and lung compliance, and lymph heart pressure development. This ability enable anurans, which have the highest rates of evaporative water loss among terrestrial vertebrates, to withstand levels of dehydration far exceeding that of other vertebrates, and to successfully occupy virtually all terrestrial environments during their evolution. Maintenance of vascular fluid volume for all vertebrates can be achieved primarily by moving fluid from the interstitial space to the vascular space by transcapillary uptake and mobilization of interstitial (lymphatic) fluid. Transcapillary fluid uptake at the capillary level has been analyzed historically by Krogh and others from a Starling perspective and involves a balance of hydrostatic and oncotic forces. A complete evaluation of blood volume homeostasis also incorporates pressures and compliances of the vascular and interstitial spaces, but has been applied to only a few species. In this review we outline the current understanding of how anurans and other vertebrates maintain blood volume during hypovolemic challenges such as dehydration and hemorrhage which is crucial for maintaining cardiac output.


© 2020 Elsevier Inc. All rights reserved.

Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.


NOTICE: this is the author’s version of a work that was accepted for publication in Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology, 254, 110878.



Persistent Identifier