Dooley P C, Williams V J
Aust J Biol Sci. 1976 Dec;29(5-6):533-44. doi: 10.1071/bi9760533.
Changes in jugular haematocrit during daily 2-h feeding periods in trained sheep with and without spleens were compared with changes in the concentration of the plasma tracer radio-iodinated human serum albumin. Jugular haematocrit was increased by 16% in intact sheep and 9% in splenectomized sheep 20 min after they started to eat dry rations. The dilution of tracer in plasma, studied after mixing in the vascular system had been completed, showed four phases. Phase 1 was the rate of removal of tracer in the period before eating began. Phase 2 was the sudden increase in plasma radioactivity that occurred in the first 20 min of eating, indicating a loss of plasma from the circulation. Phase 3 was the decrease in tracer concentration during the remaining feeding period and phase 4 was a post-feeding phase, characterized by a slower rate of decrease of tracer than during phase 3, implying that there was significant recycling of tracer during this phase. The sudden increase in plasma radioactivity, initiated by the onset of feeding, represented a reduction in plasma volume of 10-12%. Minimum plasma volume coincided with peak haematocrit values. The reduced plasma volume accounted for the increased haematocrit in splenectomized sheep, but only accounted for about half of the increase in intact sheep. The residual increase in haematocrit in intact sheep was most likely the result of splenic contraction.
将有脾和无脾的训练绵羊在每日2小时喂食期间颈静脉血细胞比容的变化与血浆示踪剂放射性碘化人血清白蛋白浓度的变化进行了比较。在完整绵羊开始吃干粮20分钟后，颈静脉血细胞比容增加了16%，在脾切除绵羊中增加了9%。在血管系统混合完成后研究的示踪剂在血浆中的稀释显示出四个阶段。阶段1是进食开始前示踪剂的清除率。阶段2是进食开始后最初20分钟内血浆放射性的突然增加，表明循环中血浆的丢失。阶段3是剩余喂食期间示踪剂浓度的降低，阶段4是喂食后阶段，其特征是示踪剂的降低速率比阶段3慢，这意味着在此阶段示踪剂有显著的再循环。由进食开始引发的血浆放射性突然增加代表血浆体积减少了10 - 12%。最小血浆体积与血细胞比容峰值一致。血浆体积的减少解释了脾切除绵羊中血细胞比容的增加，但仅占完整绵羊增加量的约一半。完整绵羊中血细胞比容的剩余增加很可能是脾收缩的结果。
