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Comparative NMR studies of diffusional water permeability of red blood cells from different species: XVIII platypus ( Ornithorhynchus anatinus) and saltwater crocodile ( Crocodylus porosus )
Author(s) -
Benga Gheorghe,
Chapman Bogdan E.,
Cox Guy C.,
Kuchel Philip W.
Publication year - 2010
Publication title -
cell biology international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 77
eISSN - 1095-8355
pISSN - 1065-6995
DOI - 10.1042/cbi20090430
Subject(s) - platypus , crocodylus , crocodile , monotreme , biology , zoology , chemistry , anatomy , ecology , systematics , taxonomy (biology)
As part of a programme of comparative measurements of P d (diffusional water permeability) the RBCs (red blood cells) from an aquatic monotreme, platypus ( Ornithorhynchus anatinus ), and an aquatic reptile, saltwater crocodile ( Crocodylus porosus ) were studied. The mean diameter of platypus RBCs was estimated by light microscopy and found to be ∼6.3 μm. P d was measured by using an Mn 2+ ‐doping 1H NMR (nuclear magnetic resonance) technique. The P d (cm/s) values were relatively low: ∼2.1×10 −3 at 25°C, 2.5×10 −3 at 30°C, 3.4×10 −3 at 37°C and 4.5 at 42°C for the platypus RBCs and ∼2.8×10 −3 at 25°C, 3.2×10 −3 at 30°C, 4.5×10 −3 at 37°C and 5.7×10 −3 at 42°C for the crocodile RBCs. In parallel with the low water permeability, the E a,d (activation energy of water diffusion) was relatively high, ∼35 kJ/mol. These results suggest that “conventional” WCPs (water channel proteins), or AQPs (aquaporins), are probably absent from the plasma membranes of RBCs from both the platypus and the saltwater crocodile.