Neural and hormonal control of arterial pressure during cold exposure in unanesthetized week-old rats.
Neural and hormonal control of arterial pressure during cold exposure in unanesthetized week-old rats.
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DOI：
10.1152/ajpregu.2001.281.5.r1514
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发表时间：
2001-11
期刊：
影响因子：
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通讯作者：
Mark S. Blumberg;T. Knoot;Robert F. Kirby
中科院分区：
文献类型：
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作者：
Mark S. Blumberg;T. Knoot;Robert F. Kirby
幼年大鼠对寒冷暴露的反应是棕色脂肪组织 (BAT) 产生的热量增加。 BAT 产热随着冷暴露的增加而稳定增加，但出现一个点，产热无法进一步增加，导致寒冷引起的心动过缓。先前的研究表明，即使心率较基线值下降 50%，平均动脉压 (MAP) 仍能保持不变。我们检查了幼犬皮下注射媒介物、α1-肾上腺素受体拮抗剂（哌唑嗪；0.5 mg/kg）、ANG II受体拮抗剂（氯沙坦；1 mg/kg）、加压素受体拮抗剂（曼宁化合物；0.5 mg/kg）或同时施用所有三种拮抗剂（三联阻滞）后，寒冷暴露期间神经和激素对外周抵抗力的影响。随着气温从热中性（即 35 摄氏度）依次降低到 29、23 和 17 摄氏度，对肩胛间温度、耗氧量、心率和动脉压进行监测。只有处于三块状态的幼崽在冷却时表现出 MAP 显着下降，尽管所有幼崽都表现出心率大幅下降。后续研究表明，封锁所有三个系统比封锁任何两个系统更有效。最后，在 17 摄氏度时，超声波发声伴随着 MAP 的显着增加，重复了之前的发现并支持发声是腹部压缩反应的声学副产品的假设，腹部压缩反应是一种有助于在心血管挑战期间维持静脉回流的操作。
Infant rats respond to cold exposure with increased heat production by brown adipose tissue (BAT). BAT thermogenesis increases steadily with increasing cold exposure, but a point occurs at which thermogenesis can increase no further, resulting in cold-induced bradycardia. Previous work has shown that mean arterial pressure (MAP) is maintained even when cardiac rate decreases as much as 50% from baseline values. We examined the neural and hormonal contributions to peripheral resistance during cold exposure after pups were injected subcutaneously with vehicle, an alpha1-adrenoceptor antagonist (prazosin; 0.5 mg/kg), an ANG II receptor antagonist (losartan; 1 mg/kg), a vasopressin receptor antagonist (Manning compound; 0.5 mg/kg), or simultaneous administration of all three antagonists (triple block). Interscapular temperature, oxygen consumption, cardiac rate, and arterial pressure were monitored as air temperature was sequentially decreased from thermoneutral (i.e., 35 degrees C) to 29, 23, and 17 degrees C. Only pups in the triple block condition exhibited significant decreases in MAP with cooling, even though all pups exhibited substantial decreases in cardiac rate. A followup study suggested that blockade of all three systems was more effective than blockade of any two systems. Finally, at 17 degrees C, ultrasonic vocalizations were accompanied by significant increases in MAP, replicating a previous finding and supporting the hypothesis that the vocalization is the acoustic by-product of the abdominal compression reaction, a maneuver that helps to maintain venous return during cardiovascular challenge.