Lash J M, Bohlen H G
Department of Physiology and Biophysics, Indiana University School of Medicine, Indianapolis 46202.
J Appl Physiol (1985). 1995 Jan;78(1):101-11. doi: 10.1152/jappl.1995.78.1.101.
These experiments determined whether a deficit in oxygen supply relative to demand could account for the sustained decrease in tissue PO2 observed during contractions of the spinotrapezius muscle in spontaneously hypertensive rats (SHR). Relative changes in blood flow were determined from measurements of vessel diameter and red blood cell velocity. Venular hemoglobin oxygen saturation measurements were performed by using in vivo spectrophotometric techniques. The relative dilation [times control (xCT)] of arteriolar vessels during contractions was as large or greater in SHR than in normotensive rats (Wistar-Kyoto), as were the increases in blood flow (2 Hz, 3.50 +/- 0.69 vs. 3.00 +/- 1.05 xCT; 4 Hz, 10.20 +/- 3.06 vs. 9.00 +/- 1.48 xCT; 8 Hz, 16.40 +/- 3.95 vs. 10.70 +/- 2.48 xCT). Venular hemoglobin oxygen saturation was lower in the resting muscle of SHR than of Wistar-Kyoto rats (31.0 +/= 3.0 vs. 43.0 +/- 1.9%) but was higher in SHR after 4- and 8-Hz contractions (4 Hz, 52.0 +/- 4.8 vs. 43.0 +/- 3.6%; 8 Hz, 51.0 +/- 4.6 vs. 41.0 +/- 3.6%). Therefore, an excess in oxygen delivery occurs relative to oxygen use during muscle contractions in SHR. The previous and current results can be reconciled by considering the possibility that oxygen exchange is limited in SHR by a decrease in anatomic or perfused capillary density, arteriovenular shunting of blood, or decreased transit time of red blood cells through exchange vessels.
这些实验确定了相对于需求而言的氧气供应不足是否能够解释在自发性高血压大鼠（SHR）斜方肌收缩期间观察到的组织氧分压持续下降。通过测量血管直径和红细胞速度来确定血流的相对变化。采用体内分光光度技术进行小静脉血红蛋白氧饱和度测量。收缩期间SHR小动脉血管的相对扩张[相对于对照的倍数（xCT）]与正常血压大鼠（Wistar-Kyoto）一样大或更大，血流增加情况也是如此（2Hz时，3.50±0.69 vs. 3.00±1.05 xCT；4Hz时，10.20±3.06 vs. 9.00±1.48 xCT；8Hz时，16.40±3.95 vs. 10.70±2.48 xCT）。SHR静息肌肉中的小静脉血红蛋白氧饱和度低于Wistar-Kyoto大鼠（31.0±3.0 vs. 4十三条，43.0±1.9%），但在4Hz和8Hz收缩后SHR中的小静脉血红蛋白氧饱和度更高（4Hz时，52.0±4.8 vs. 43.0±3.6%；8Hz时，51.0±4.6 vs. 41.0±3.6%）。因此，在SHR肌肉收缩期间，相对于氧气利用而言出现了氧气输送过量的情况。通过考虑以下可能性可以使先前和当前的结果相协调，即SHR中氧交换受到限制可能是由于解剖学或灌注毛细血管密度降低、血液的动静脉分流或红细胞通过交换血管的转运时间缩短。
