Minimal volume regulation after shrinkage of red blood cells from five species of reptiles
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Data
2008-05-01
Autores
Kristensen, Karina
Berenbrink, Michael
Koldkjaer, Pia
Abe, Augusto Shinya [UNESP]
Wang, Tobias
Título da Revista
ISSN da Revista
Título de Volume
Editor
Elsevier B.V.
Resumo
Red blood cells (RBCs) from most vertebrates restore volume upon hypertonic shrinkage and the mechanisms underlying this regulatory volume increase (RVI) have been studied extensively in these cells. Despite the phylogenetically interesting position of reptiles, very little is known about their red cell function. The present study demonstrates that oxygenated RBCs in all major groups of reptiles exhibit no or a very reduced RVI upon -25% calculated hyperosmotic shrinkage. Thus, RBCs from the snakes Crotalus durissus and Python regius, the turtle Trachemys scripta and the alligator Alligator mississippiensis showed no statistically significant RVI within 120 min after shrinkage, while the lizard Tupinambis merianae showed 22% volume recovery after 120 min. Amiloride (10(-4) M) and bumetanide (10(-5) M) had no effect on the RVI in T merianae, indicating no involvement of the Na(+)/H(+) exchanger (NHE) or the Na(+)/K(+)/2Cl(-) co-transporter (NKCC) or insentive transporters. Deoxygenation of RBCs from A. mississippiensis and T merianae did not significantly affect RVI upon shrinkage. Deoxygenation per se of red blood cells from T merianae elicited a slow volume increase, but the mechanism was not characterized. It seems, therefore, that the RVI response based on NHE activation was lost among the early sauropsids that gave rise to modern reptiles and birds, while it was retained in mammals. An RVI response has then reappeared in birds, but based on activation of the NKCC. Alternatively, the absence of the RVI response may represent the most ancient condition, and could have evolved several times within vertebrates. (C) 2008 Elsevier B.V. All rights reserved.
Descrição
Palavras-chave
red blood cells, volume regulation, regulatory volume increase, Na plus /H plus exchanger, Na+/K+/2Cl-co-transporter, reptile
Como citar
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology. New York: Elsevier B.V., v. 150, n. 1, p. 46-51, 2008.