Malvin G M, Wood S C
Oxygen Transport Program, Lovelace Medical Foundation, Albuquerque, New Mexico 87108.
J Appl Physiol (1985). 1992 Jul;73(1):224-33. doi: 10.1152/jappl.1992.73.1.224.
We tested experimentally the hypothesis that decreasing capillary red blood cell (RBC) density (dRBC) reduces the tissue diffusing capacity of frog skin to CO (DtiCO) and O2 (DtiO2). The effects of dRBC on CO2 transport were also assessed. C18O, O2, and CO2 transport between the skin and a cutaneous sample chamber on the belly of anesthetized (halothane) frogs (Rana pipiens) was measured by mass spectrometry, and the cutaneous conductances to C18O (GCO), O2 (GO2), and CO2 (GCO2) were calculated. The dRBC of the planar cutaneous capillary bed was measured by intravital fluorescent video microscopy. DtiCO and DtiO2 were calculated from a modification of the Roughton-Foster equation: 1/G = 1/Dti + 1/(theta RBC.dRBC), where theta RBC values were estimated from literature values. In one group of animals (n = 6), measurements were made before hemodilution (dRBC = 630 +/- 56 cells/mm2), after one hemodilution (dRBC = 349 +/- 50 cells/mm2), and after a second hemodilution (dRBC = 150 +/- 31 cells/mm2). In controls, time had no effect on GCO, GO2, or GCO2 (P greater than 0.42). Before hemodilution, GCO, GO2, and GCO2 were 0.069 +/- 0.010, 0.088 +/- 0.0012, and 1.23 +/- 0.010 nmol.min-1.Torr-1.cm-2, respectively, and lowering dRBC by hemodilution decreased all these parameters (P less than 0.025). The mean slopes of GCO, GO2, and GCO2 vs. dRBC were 6.0 +/- 1.3 x 10(-7), 7.2 +/- 2.3 x 10(-7), and 7.8 +/- 3.0 x 10(-6) nmol.min-1.Torr-1.RBC-1, respectively. Lowering dRBC also decreased DtiCO and DtiO2 (P less than 0.034). DtiCO and DtiO2 were 0.080 +/- 0.012 and 0.096 +/- 0.013 nmol.min-1.Torr-1.cm-2, respectively, before hemodilution. The mean slopes of DtiCO and DtiO2 vs. dRBC were 4.9 +/- 2.1 x 10(-7) and 6.5 +/- 2.8 x 10(-7) nmol.min-1.Torr-1.RBC-1, respectively. Hemodilution had no effect on perfused capillary density (P = 0.38). These results indicate that tissue diffusive conductance is proportional to dRBC. Regulation of dRBC may be an important mechanism modulating diffusive gas transport in tissue.
降低毛细血管红细胞（RBC）密度（dRBC）会降低蛙皮对一氧化碳（CO）和氧气（O₂）的组织扩散能力（DtiCO和DtiO₂）。同时还评估了dRBC对二氧化碳运输的影响。通过质谱法测量了麻醉（氟烷）青蛙（豹蛙）腹部皮肤与皮肤样品室之间¹⁸CO、O₂和CO₂的运输情况，并计算了皮肤对¹⁸CO（GCO）、O₂（GO₂）和CO₂（GCO₂）的传导率。通过活体荧光视频显微镜测量平面皮肤毛细血管床的dRBC。DtiCO和DtiO₂根据对Roughton - Foster方程的修正计算得出：1/G = 1/Dti + 1/(θRBC·dRBC)，其中θRBC值根据文献值估算。在一组动物（n = 6）中，在血液稀释前（dRBC = 630 ± 56个细胞/mm²）、一次血液稀释后（dRBC = 349 ± 50个细胞/mm²）和第二次血液稀释后（dRBC = 150 ± 31个细胞/mm²）进行了测量。在对照组中，时间对GCO、GO₂或GCO₂没有影响（P大于0.42）。血液稀释前，GCO、GO₂和GCO₂分别为0.069 ± 0.010、0.088 ± 0.0012和1.23 ± 0.010 nmol·min⁻¹·Torr⁻¹·cm⁻²，通过血液稀释降低dRBC会降低所有这些参数（P小于0.025）。GCO、GO₂和GCO₂与dRBC的平均斜率分别为6.0 ± 1.3×10⁻⁷、7.2 ± 2.3×10⁻⁷和7.8 ± 3.0×10⁻⁶ nmol·min⁻¹·Torr⁻¹·RBC⁻¹。降低dRBC也会降低DtiCO和DtiO₂（P小于0.034）。血液稀释前，DtiCO和DtiO₂分别为0.080 ± 0.012和0.096 ± 0.013 nmol·min⁻¹·Torr⁻¹·cm⁻²。DtiCO和DtiO₂与dRBC的平均斜率分别为4.9 ± 2.1×10⁻⁷和6.5 ± 2.8×10⁻⁷ nmol·min⁻¹·Torr⁻¹·RBC⁻¹。血液稀释对灌注毛细血管密度没有影响（P = 0.38）。这些结果表明组织扩散传导率与dRBC成正比。调节dRBC可能是调节组织中气体扩散运输的重要机制。
