Fillenz M, Stanford S C, Coles B G
University Laboratory of Physiology, Oxford, England.
J Neurochem. 1993 Jul;61(1):132-7. doi: 10.1111/j.1471-4159.1993.tb03547.x.
Changes in sympathetic nerve terminals of the heart after varying periods of exposure of rats to 4 degrees C were investigated. Two indices were used for changes in the number of noradrenaline storage vesicles, i.e., vesicular dopamine beta-hydroxylase (DBH) activity and noradrenaline storage capacity. The latter was obtained after uptake of [3H]noradrenaline; endogenous content, uptake of exogenous noradrenaline, and degree of saturation of the vesicles were calculated using the specific activity of the [3H]noradrenaline. As a measure of tyrosine hydroxylase activity, whole ventricular noradrenaline, dopamine, and dihydroxyphenylacetic acid content were used. After 4 h of cold exposure there was an increase in vesicular endogenous noradrenaline content, uptake, storage capacity, and DBH activity as well as a large increase in whole ventricular dopamine. After 6 h in the cold, vesicular endogenous noradrenaline content, storage capacity, and DBH activity were decreased. The results suggest that during cold exposure there is an initial increase followed by a decrease in the number of functional vesicles in the nerve terminal, which could explain the fluctuations in the rate of noradrenaline release.
研究了大鼠在4℃环境下暴露不同时长后心脏交感神经末梢的变化。采用两个指标来评估去甲肾上腺素储存囊泡数量的变化，即囊泡多巴胺β-羟化酶（DBH）活性和去甲肾上腺素储存能力。后者是在摄取[3H]去甲肾上腺素后测得的；利用[3H]去甲肾上腺素的比活性计算内源性含量、外源性去甲肾上腺素摄取量以及囊泡的饱和度。作为酪氨酸羟化酶活性的指标，采用了整个心室的去甲肾上腺素、多巴胺和二羟基苯乙酸含量。冷暴露4小时后，囊泡内源性去甲肾上腺素含量、摄取量、储存能力和DBH活性增加，同时整个心室的多巴胺大幅增加。冷暴露6小时后，囊泡内源性去甲肾上腺素含量、储存能力和DBH活性降低。结果表明，在冷暴露期间，神经末梢功能性囊泡数量最初增加，随后减少，这可以解释去甲肾上腺素释放速率的波动。
