Major T C, Schwinghamer J M, Winston S
Am J Physiol. 1981 Jun;240(6):H868-73. doi: 10.1152/ajpheart.1981.240.6.H868.
Vascular resistance and capacitance were studied in innervated or denervated canine forelimbs. Hypothermia (38-28 degrees C) was induced systemically, by external cooling of blood which returned to the right heart, or locally, by cooling blood perfusing the forelimb. Systemic cooling to 33 and then to 28 degrees C elicited significant decreases in limb weight with substantial increases in both skin and skeletal muscle vascular resistances. Acute denervation of the forelimbs attenuated both the fall in limb weight and increase in skin vascular resistance associated with cooling. These data support the contention that cutaneous vasoconstriction during systemic cooling is mediated primarily by sympathetic nerves, whereas skeletal muscle vasoconstriction is mediated primarily by circulating hormones. Local cooling elicited skin and skeletal muscle vascular dilation at 33 degrees C in both innervated and denervated forelimbs whereas either no change or a slight increase in skin and skeletal muscle vascular resistance resulted upon local cooling to 28 degrees C, perhaps due to the inhibition of Na+ - K+ - ATPase activity and/or a rise in blood viscosity. The locally induced vasodilation was found to override the powerful vasoconstrictor response caused by systemic cooling. The vasodilation is considered active rather than passive, because the increase in forelimb weight and decreases in forelimb vascular resistances occurred in the denervated as well as innervated limbs.
在有神经支配或去神经支配的犬前肢中研究了血管阻力和容量。通过冷却回流至右心的血液进行全身低温诱导（38 - 28摄氏度），或通过冷却灌注前肢的血液进行局部低温诱导。全身冷却至33摄氏度然后再至28摄氏度会导致肢体重量显著下降，同时皮肤和骨骼肌血管阻力大幅增加。前肢急性去神经支配减弱了与冷却相关的肢体重量下降和皮肤血管阻力增加。这些数据支持以下观点，即全身冷却期间的皮肤血管收缩主要由交感神经介导，而骨骼肌血管收缩主要由循环激素介导。在有神经支配和去神经支配的前肢中，局部冷却在33摄氏度时引起皮肤和骨骼肌血管扩张，而局部冷却至28摄氏度时，皮肤和骨骼肌血管阻力要么没有变化，要么略有增加，这可能是由于Na + - K + - ATP酶活性受到抑制和/或血液粘度升高所致。发现局部诱导的血管扩张可克服全身冷却引起的强烈血管收缩反应。这种血管扩张被认为是主动的而非被动的，因为在去神经支配和有神经支配的肢体中均出现前肢重量增加和前肢血管阻力降低的情况。
