Maturation of catecholamine response and extraneuronal uptake in rabbit trachea.
Maturation of catecholamine response and extraneuronal uptake in rabbit trachea.
复制标题
兔气管中儿茶酚胺反应和神经元外摄取的成熟。
DOI：
10.1152/ajplung.1994.266.3.l217
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Schramm,CM
中科院分区：
文献类型：
--
作者：
Varlotta,L;Schramm,CM
本研究调查了神经元外儿茶酚胺清除率的成熟变化是否解释了兔气管段异丙肾上腺素反应性的个体发育减弱。用乙酰胆碱 (ACh) 或 KCl 进行半最大收缩后，从新生兔、1 月龄兔和成年兔中分离出的气管环段 (TS) 随着异丙肾上腺素的累积给药而松弛。随着出生后的成熟，ACh 和 KCl 收缩的 TS 中的最大松弛度和对异丙肾上腺素的敏感性均显着下降。用甲基强的松龙抑制神经元外儿茶酚胺的摄取导致 1 个月和成人对异丙肾上腺素的敏感性增强，但对新生儿气管段没有影响。在单独的研究中，直接测定从相似年龄的兔子分离的气管段的神经元外儿茶酚胺摄取，并用神经元摄取和单胺氧化酶抑制剂预处理。气管组织中[3H]去甲肾上腺素的最大神经元外摄取随着年龄的增长而显着降低。相反，摄取过程对去甲肾上腺素的敏感性随着年龄的增长而增加。兔气管段的相对儿茶酚胺储备随着年龄的增长而显着下降，并且与用乙酰胆碱或氯化钾预收缩的年龄匹配的 TS 中β-肾上腺素儿茶酚胺、异丙肾上腺素引起的最大松弛程度直接相关。这些发现表明，随着成熟，神经元外的摄取更有效地与β-肾上腺素受体刺激竞争，因此可能导致兔气管组织中β-肾上腺素能反应性的个体发育减弱。
The present study investigated whether maturational changes in extraneuronal catecholamine clearance accounted for the ontogenetic attenuation of isoproterenol responsiveness in rabbit tracheal segments. Following half-maximal contraction with acetylcholine (ACh) or KCl, tracheal ring segments (TS) isolated from newborn, 1-mo, and adult rabbits were relaxed with cumulative administration of isoproterenol. With postnatal maturation, there occurred a significant decrease in both maximal relaxation and sensitivity to isoproterenol in both ACh- and KCl-contracted TS. Inhibition of extraneuronal catecholamine uptake with methylprednisolone resulted in enhanced sensitivity to isoproterenol in 1-mo and adult, but not in newborn tracheal segments. In separate studies, extraneuronal catecholamine uptake was directly assayed in tracheal segments isolated from rabbits of similar age and pretreated with neuronal uptake and monoamine oxidase inhibitors. Maximal extraneuronal uptake of [3H]norepinephrine significantly decreased with age in tracheal tissues. In contrast, the sensitivity of the uptake process to norepinephrine increased with age. The relative catecholamine reserve markedly decreased with age in rabbit tracheal segments and was directly related to the maximal degree of relaxation elicited with the beta-adrenergic catecholamine, isoproterenol, in age-matched TS precontracted with either ACh or KCl. These findings suggest that, with maturation, extraneuronal uptake more effectively competes with beta-adrenoreceptor stimulation and, accordingly, may contribute to the ontogenetic attenuation of beta-adrenergic responsiveness in rabbit tracheal tissues.