Andrianakis P, Walker D
Department of Physiology, Monash University, Clayton, Victoria, Australia.
Exp Physiol. 1994 Jan;79(1):1-13. doi: 10.1113/expphysiol.1994.sp003735.
Uterine and umbilical blood flows were measured in pregnant sheep (125-142 days gestation) under normothermic and hyperthermic conditions using the Fick principle with [14C]antipyrine as the indicator. Exposure of the sheep to an ambient temperature of 43 +/- 1 degrees C (25-30% relative humidity) for 8 h increased maternal and fetal core temperatures 1.19 +/- 0.15 and 1.39 +/- 0.12 degrees C respectively. Maternal hyperventilation caused a significant decrease of both maternal and fetal arterial partial pressure of CO2 (Pa,CO2) and increase of arterial pH. Uterine blood flow increased significantly during the hyperthermia (+54.2 +/- 14.1%), the increase being correlated with the magnitude of the decrease of maternal Pa,CO2 (r = -0.84, P < 0.05) but not with the increase of maternal core temperature. The increase of uterine blood flow was not associated with a concomitant increase in the placental clearance of [14C]antipyrine, a result which could arise if the increase of blood flow was non-placental (i.e. did not occur within the cotyledons), or occurred through uterine arteriovenous shunts during the period of heat stress. Hyperthermia was not associated with a significant change of umbilical blood flow, placental transfer of glucose, or fetal glucose uptake. Since the loss of heat from the fetus occurs mainly across the placenta, we speculate that the apparent increase of uterine blood flow during maternal hyperthermia has an adaptive significance by maintaining conductive heat flux in a fetomaternal direction, even though cotyledonary (placental) blood flows did not increase.
在正常体温和高温条件下，以[14C]安替比林为指示剂，运用菲克原理对妊娠绵羊（妊娠125 - 142天）的子宫和脐血流进行了测量。将绵羊置于43±1℃的环境温度（相对湿度25 - 30%）下8小时，母体和胎儿的核心体温分别升高了1.19±0.15℃和1.39±0.12℃。母体过度通气导致母体和胎儿动脉血二氧化碳分压（Pa,CO2）显著降低，动脉血pH值升高。高温期间子宫血流量显著增加（+54.2±14.1%），这种增加与母体Pa,CO2的降低幅度相关（r = -0.84，P < 0.05），但与母体核心体温的升高无关。子宫血流量的增加与[14C]安替比林的胎盘清除率的相应增加无关，这一结果可能是由于血流量的增加并非发生在胎盘内（即未在子叶内发生），或者是在热应激期间通过子宫动静脉分流发生的。高温与脐血流量、葡萄糖的胎盘转运或胎儿葡萄糖摄取的显著变化无关。由于胎儿的散热主要通过胎盘进行，我们推测母体高温期间子宫血流量的明显增加具有适应性意义，即通过维持母胎方向的传导热通量，尽管子叶（胎盘）血流量并未增加。
