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Excessive Erythrocytosis Does Not Elevate Capillary Oxygen Delivery in Subcutaneous Mouse Tissue
Author(s) -
FRIETSCH THOMAS,
GASSMANN MAX,
GROTH GESINE,
Waschke KLAUS F.,
VOGEL JOHANNES,
CABRALES PEDRO,
VAJKOCZI PETER,
DORNBEINEKE ALEXANDRA,
INTAGLIETTA MARCOS,
KERGER HEINZ
Publication year - 2007
Publication title -
microcirculation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.793
H-Index - 83
eISSN - 1549-8719
pISSN - 1073-9688
DOI - 10.1080/10739680601131200
Subject(s) - oxygen delivery , subcutaneous tissue , chemistry , subcutaneous injection , oxygen , medicine , pathology , organic chemistry
Objective: Acclimatization to reduced environmental oxygen includes erythropoietin‐regulated increase in erythrocytes enhancing the blood's oxygen content. However, increased hematocrit levels result in elevated blood viscosity that might impair microcirculation and tissue oxygenation. To assess this oxygen supply to the skin, the authors used erythropoietin overexpressing transgenic mice (tg6) that develop excessive erythrocytosis in an oxygen‐independent manner. These animals have been previously reported to elevate their blood viscosity 4‐fold. Methods: The partial oxygen pressure ( p O 2 ) distribution was evaluated in microvessels as well as in subcutaneous interstitial tissue within a dorsal skinfold chamber of resting conscious mice using automated phosphorescence quenching. Results: Compared to wildtype (wt) animals, transgenic blood viscosity increased 4‐fold but microvessel diameter was not altered. Despite sharing similar blood p O 2 as the wt siblings, tg6 animals nearly doubled their oxygen content. Moreover, tg6 erythrocytes reduced hemoglobin's oxygen affinity by decreased 2,3‐DPG levels and an increased Hill number. Transgenic arterioles and venules showed increased p O 2 compared to wt controls whereas capillary and tissue p O 2 were not altered. Conclusions: Excessive erythrocytosis does not elevate capillary oxygen delivery.