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High affinity of blood for oxygen reduces oxygen uptake in contracting canine gracilis muscle
Author(s) -
Kohzuki H,
Enoki Y,
Sakata S,
Shimizu S,
Ohga Y
Publication year - 1994
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1113/expphysiol.1994.sp003743
Subject(s) - perfusion , pco2 , chemistry , oxygen , blood flow , oxygen delivery , gracilis muscle , p50 , oxygen saturation , arterial blood , medicine , endocrinology , biochemistry , organic chemistry , transcription factor , gene
To clarify the influence of blood flow with high‐oxygen (O2)‐affinity blood on oxygen consumption (VO2) in submaximally exercising skeletal muscle, we perfused the isolated dog gracilis (n = 8) contracting under 1 Hz stimulation alternatively with normal and high‐O2‐affinity blood, with a constant arterial O2 content (Ca,O2) and varying perfusion rates. The average P50 (oxygen partial pressure (PO2) for half‐saturation at pH 7.40, PCO2 of 40 mmHg at 37 degrees C) of the high‐O2‐affinity blood prepared by carbamylation was 15.5 mmHg, and that of the normal blood 33.7 mmHg. With normal blood perfusion, the average VO2 above 6 ml min‐1 (100 g)‐1 of O2 delivery (Ca,O2 x flow) was 4.38 ml min‐1 (100 g)‐1 (range 4.17–4.68 ml min‐1 (100 g)‐1, and VO2 at the O2 delivery range of 6–5 and 4‐2.5 ml min‐1 (100 g)‐1 decreased to 3.96 and 2.43 ml min‐1 (100 g)‐1, respectively. The PO2 of venous effluent (Pv,O2) at the O2 delivery of 6 ml min‐1 (100 g)‐1 was 33 mmHg. With low‐P50 blood perfusion, VO2 was significantly less than with normal blood, both below the O2 delivery level of 6 ml min‐1 (100 g)‐1 and above it, even in the fairly high O2 delivery range of 8.5–12 ml min‐1 (100 g)‐1 (P < 0.05). Thus, high blood flow did not compensate for the reduced VO2 caused by high‐O2‐affinity blood. At values of Pv,O2 less than 33 mmHg, VO2 with low‐P50 blood was not significantly different from that with normal blood (P > 0.05). The reduced VO2 in submaximally exercising skeletal muscle might be due to a slower O2 dissociation from the high‐O2‐affinity red cells and to a limited O2 diffusion resulting from the lower Pv,O2 value (which reflects mean end‐capillary PO2).