Kohzuki H, Enoki Y, Sakata S, Shimizu S, Ohga Y
Second Department of Physiology, Nara Medical University, Japan.
Exp Physiol. 1994 Jan;79(1):71-80. doi: 10.1113/expphysiol.1994.sp003743.
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).
为了阐明高氧亲和力血液的血流对亚极量运动骨骼肌氧消耗（VO₂）的影响，我们以恒定的动脉血氧含量（Ca,O₂）和不同的灌注速率，交替用正常血液和高氧亲和力血液灌注在1Hz刺激下收缩的离体犬股薄肌（n = 8）。通过氨甲酰化制备的高氧亲和力血液在pH 7.40、37℃时PCO₂为40mmHg条件下的平均P50（半饱和氧分压（PO₂））为15.5mmHg，正常血液的平均P50为33.7mmHg。正常血液灌注时，氧输送（Ca,O₂×流量）高于6ml·min⁻¹（100g）⁻¹时的平均VO₂为4.38ml·min⁻¹（100g）⁻¹（范围为4.17 - 4.68ml·min⁻¹（100g）⁻¹），在氧输送范围为6 - 5ml·min⁻¹（100g）⁻¹和4 - 2.5ml·min⁻¹（100g）⁻¹时，VO₂分别降至3.96和2.43ml·min⁻¹（100g）⁻¹。氧输送为6ml·min⁻¹（100g）⁻¹时静脉流出液的PO₂（Pv,O₂）为33mmHg。低P50血液灌注时，即使在8.5 - 12ml·min⁻¹（100g）⁻¹的相当高的氧输送范围内，低于6ml·min⁻¹（100g）⁻¹的氧输送水平以及高于该水平时，VO₂均显著低于正常血液灌注时（P < 0.05）。因此，高血流量并不能补偿高氧亲和力血液导致的VO₂降低。当Pv,O₂值小于33mmHg时，低P50血液的VO₂与正常血液的VO₂无显著差异（P > 0.05）。亚极量运动骨骼肌中VO₂降低可能是由于高氧亲和力红细胞的氧解离较慢以及较低的Pv,O₂值（反映平均毛细血管末端PO₂）导致的氧扩散受限。
