Bell A W, Hales J R, King R B, Fawcett A A
J Appl Physiol Respir Environ Exerc Physiol. 1983 Dec;55(6):1916-23. doi: 10.1152/jappl.1983.55.6.1916.
Radioactive microspheres were used to measure cardiac output and blood flow to most major tissues in sheep at rest and during treadmill exercise (3- to 6-fold increase in metabolic rate for 30 min) in thermoneutral (TN) [dry bulb temperature (Tdb) = 16 degrees C, wet bulb temperature (Twb) = 12 degrees C] and mildly hot (MH) (Tdb = 40 degrees C, Twb = 23 degrees C) environments. During exercise, rectal temperature increased more under MH than under TN conditions; exercise-induced changes in the major central cardiovascular parameters were unaffected by MH. Exercise in TN caused mild hypocapnia, and in MH, severe respiratory alkalosis. Skin blood flow in the torso decreased during exercise in TN and MH. Extremity skin blood flow was increased by heat but not exercise. Exercise-induced increases in flows to respiratory muscles and upper respiratory tract tissues were greatly enhanced in MH. Exercise caused large increases in blood flow to fore- and hindlimb muscles, which were less in MH than in TN. Effects of MH on exercise-induced changes in flow to these and other tissues (e.g., abdominal viscera and adipose tissue) are discussed in terms of the conflicting requirements of energy expenditure and body temperature regulation during exercise in sheep and other species, particularly humans.
放射性微球被用于测量绵羊在静息状态以及在热中性（TN）[干球温度（Tdb）=16℃，湿球温度（Twb）=12℃]和轻度炎热（MH）（Tdb = 40℃，Twb = 23℃）环境下跑步机运动期间（代谢率在30分钟内增加3至6倍）的心输出量和流向大多数主要组织的血流量。在运动期间，直肠温度在MH环境下比在TN条件下升高得更多；运动引起的主要中心心血管参数的变化不受MH的影响。在TN环境下运动导致轻度低碳酸血症，而在MH环境下则导致严重呼吸性碱中毒。在TN和MH环境下运动期间，躯干皮肤血流量减少。肢体皮肤血流量因受热而增加，但不受运动影响。在MH环境下，运动引起的流向呼吸肌和上呼吸道组织的血流量增加显著增强。运动导致前肢和后肢肌肉的血流量大幅增加，在MH环境下增加的幅度小于在TN环境下。就绵羊和其他物种（尤其是人类）运动期间能量消耗和体温调节的相互冲突的需求而言，讨论了MH对运动引起的这些组织和其他组织（如腹部内脏和脂肪组织）血流量变化的影响。
