Manohar M, Parks C M, Busch M A, Bisgard G E
J Surg Res. 1985 Dec;39(6):499-509. doi: 10.1016/0022-4804(85)90118-0.
Regional myocardial blood flow (MBF; 15-micron-diam radionuclide-labeled microspheres) was studied in six unanesthetized calves sojourning at 3500 m (PB = 500 mm Hg) for 53 +/- 2 days. These high-altitude (HA)-exposed calves were studied during chronic hypoxemia (PaO2 = 48 +/- 1 mm Hg), maximal coronary vasodilation, and during acute normoxemia (PaO2 = 91 +/- 1 mm Hg). Nine calves born and raised at sea level (SL) were also studied at matched PaO2 during chronic normoxemia, maximal coronary vasodilation, and acute hypoxemia to serve as control. Marked pulmonary hypertension and right ventricular (RV) hypertrophy were present in HA calves. Left ventricular (LV) MBF of HA calves during chronic hypoxemia (1.05 +/- 0.11 ml X min-1 X g-1) was similar to that of normoxemic SL calves (1.11 +/- 0.06 ml X min-1 X g-1) but MBF in their hypertrophied RV (1.65 +/- 0.21 ml X min-1 X g-1) exceeded that in normoxemic SL calves (0.47 +/- 0.06 ml X min-1 X g-1). More interesting was the finding that RV and LV MBF of HA calves did not change between chronic hypoxemia and acute normoxemia. By contrast, acute hypoxemia of a similar degree caused a dramatic increase in RV as well as LV MBF of SL calves. Minimal LV coronary vascular resistance was similar in the two groups of calves. This meant that functional cross-sectional area of LV coronary vascular bed was not altered in response to sojourn at HA. Minimal RV coronary vascular resistance of HA calves was also not different from that of SL calves. This means that functional cross-sectional area of the RV coronary vascular bed in HA calves increased proportionately with the increase in their RV mass.
对6只未麻醉的小牛进行了区域心肌血流量（MBF；直径15微米的放射性核素标记微球）研究，这些小牛在海拔3500米（PB = 500 mmHg）的环境中停留了53±2天。对这些暴露于高海拔（HA）环境的小牛在慢性低氧血症（PaO2 = 48±1 mmHg）、最大冠状动脉扩张以及急性正常氧血症（PaO2 = 91±1 mmHg）期间进行了研究。还对9只在海平面（SL）出生并长大的小牛在慢性正常氧血症、最大冠状动脉扩张以及急性低氧血症期间，在匹配的PaO2水平下进行了研究，作为对照。HA小牛存在明显的肺动脉高压和右心室（RV）肥厚。HA小牛在慢性低氧血症期间的左心室（LV）MBF（1.05±0.11 ml·min-1·g-1）与正常氧血症的SL小牛（1.11±0.06 ml·min-1·g-1）相似，但它们肥厚的RV中的MBF（1.65±0.21 ml·min-1·g-1）超过了正常氧血症的SL小牛（0.47±0.06 ml·min-1·g-1）。更有趣的是，HA小牛的RV和LV MBF在慢性低氧血症和急性正常氧血症之间没有变化。相比之下，类似程度的急性低氧血症会导致SL小牛的RV以及LV MBF显著增加。两组小牛的最小LV冠状动脉血管阻力相似。这意味着LV冠状动脉血管床的功能横截面积不会因在HA环境中的停留而改变。HA小牛的最小RV冠状动脉血管阻力也与SL小牛没有差异。这意味着HA小牛RV冠状动脉血管床的功能横截面积随着其RV质量的增加而成比例增加。
