ACTIVATION OF PREJUNCTIONAL BETA-ADRENOCEPTORS IN RAT ATRIA BY ADRENALINE APPLIED EXOGENOUSLY OR RELEASED AS A CO-TRANSMITTER
ACTIVATION OF PREJUNCTIONAL BETA-ADRENOCEPTORS IN RAT ATRIA BY ADRENALINE APPLIED EXOGENOUSLY OR RELEASED AS A CO-TRANSMITTER
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DOI：
10.1111/j.1476-5381.1981.tb16802.x
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发表时间：
1981-01-01
影响因子：
7.3
通讯作者：
TUNG, LH
中科院分区：
文献类型：
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作者：
MAJEWSKI, H;RAND, MJ;TUNG, LH
1肾上腺素（10 nM）显著增强了刺激诱导的放射性从预先与[3 H]-去甲肾上腺素（[3 H]-NA）孵育的大鼠心房流出。美托洛尔（0.1 μm）可消除该效应。2较高浓度（1μm）的肾上腺素和NA（1μm）可显著降低刺激诱导的放射性外排。然而，在酚苄明（10μm）的存在下，肾上腺素（1μm）增强流出，而NA（1μm）没有影响。3在大鼠离体心房中，肾上腺素预孵育，然后与NA孵育，两种儿茶酚胺被吸收，并通过场刺激释放。当与肾上腺素预孵育并与[3 H]-NA孵育时，美托洛尔降低了刺激诱导的放射性外排。如果心房与NA而不是肾上腺素预孵育，则不会发生这种效应，表明神经元释放的肾上腺素激活了连接前β肾上腺素受体。4在清醒大鼠中，静脉注射肾上腺素（6.0和0.6 nmol/kg）并保留在心房中，并可通过场刺激释放。给药后24 h内，这些大鼠的释放呈钙依赖性。
1Adrenaline (10 nM) significantly enhanced the stimulation‐induced efflux of radioactivity from rat atria previously incubated with [3H]‐noradrenaline ([3H]‐NA). This effect was abolished by metoprolol (0.1 μm).2Adrenaline in a higher concentration (1μm) and NA (1μm) significantly reduced the stimulation‐induced efflux of radioactivity. However, in the presence of phenoxybenzamine (10μm), adrenaline (1μm) enhanced the efflux, whereas NA (1μm) had no effect.3In rat isolated atria pre‐incubated with adrenaline and then incubated with NA, both catecholamines were taken up and were released by field stimulation. When pre‐incubation was with adrenaline and incubation was with [3H]‐NA, metoprolol decreased the stimulation‐induced efflux of radioactivity. This effect did not occur if the atria were pre‐incubated with NA instead of adrenaline, suggesting that neuronally released adrenaline activates prejunctional β‐adrenoceptors.4In conscious rats, intravenously administered adrenaline (6.0 and 0.6 nmol/kg) was taken up and retained in the atria and could be released by field stimulation. The release was calcium‐dependent from these rats up to 24 h after administration.