The role of cyclic AMP and its protein kinase in mediating acetylcholine release and the action of adenosine at frog motor nerve endings.
The role of cyclic AMP and its protein kinase in mediating acetylcholine release and the action of adenosine at frog motor nerve endings.
复制标题
环AMP及其蛋白激酶在介导乙酰胆碱释放中的作用以及腺苷在青蛙运动神经末梢的作用。
DOI：
10.1111/j.1476-5381.1990.tb12707.x
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发表时间：
1990
影响因子：
7.3
通讯作者：
Solsona,CS
中科院分区：
文献类型：
--
作者：
Hirsh,JK;Silinsky,EM;Solsona,CS
1在蛙运动神经末梢研究了环磷酸腺苷（cAMP）及其蛋白激酶（PKA）对乙酰胆碱（ACh）释放的促进作用。还研究了环AMP依赖性蛋白磷酸化对腺苷受体激动剂作用的影响。2使用磷脂囊泡（脂质体）作为载体，将环AMP递送至运动神经末梢质膜下方的细胞质局部区域。在大多数实验中，脂质体中的环AMP产生了诱发ACh释放（m）和自发ACh释放（微型终板电位频率; m. e. p. p. f）平均水平的平行降低。这些抑制作用的环AMP的量子ACh释放类似于腺苷的行动。3使用亲脂性环AMP类似物的细胞质环AMP浓度的全球增加的影响一般与环AMP观察到的不同。8-（4-氯苯硫基）环AMP（CPT环AMP）使m和m.e.p.p.f.增加约2倍。二丁酰环磷酸腺苷（db环磷酸腺苷）也增加m和m. e. p. p. f，与m的影响是较小的，更多变。4所有三个环磷酸腺苷类似物减少腺苷受体激动剂的自发和诱发ACh释放的影响。5蛋白磷酸化介导的ACh释放的作用和腺苷的抑制作用进行了研究与蛋白激酶抑制剂H7。H7（30-100 μm）对诱发或自发ACh释放无一致性影响。然而，在这些浓度下，H7对烟碱型ACh受体/离子通道产生了不幸的抑制作用。6 H7阻止了CPT环AMP（250 μm）产生的自发ACh释放的增加。因此，H7可能抑制蛙运动神经末梢中的PK A。7 H7没有改变腺苷对诱发和自发ACh释放的抑制作用。（i）腺苷酸环化酶-环AMP-PK A系统在运动神经末梢内被区室化，（ii）磷酸化在ACh释放中不起主要作用，和（iii）环AMP-PKA系统调节而不是介导腺苷的抑制作用。
1The importance of adenosine 3′:5′‐cyclic monophosphate (cyclic AMP) and its protein kinase (protein kinase A, PKA) in promoting acetylcholine (ACh) release was studied at frog motor nerve endings. The effects of cyclic AMP‐dependent protein phosphorylation on the action of adenosine receptor agonists were also investigated.2Cyclic AMP was delivered to a local region of the cytoplasm just beneath the plasma membrane of motor nerve endings using phospholipid vesicles (liposomes) as a vehicle. Cyclic AMP in liposomes produced a parallel reduction in the mean level of evoked ACh release (m) and spontaneous ACh release (miniature endplate potential frequency; m.e.p.p.f) in most experiments. These inhibitory effects of cyclic AMP on quantal ACh release resemble the action of adenosine.3The effects of global increases in cytoplasmic cyclic AMP concentrations using lipophilic cyclic AMP analogues were generally different from those observed with cyclic AMP. 8‐(4‐Chlorophenylthio) cyclic AMP (CPT cyclic AMP) produced approximately two fold increases in m and m.e.p.p.f. Dibutyryl cyclic AMP (db cyclic AMP) also increased m and m.e.p.p.f, with the effect on m being smaller and more variable.4All three cyclic AMP analogues reduced the effects of adenosine receptor agonists on spontaneous and evoked ACh release.5The roles of protein phosphorylation in mediating ACh release and the inhibitory effects of adenosine were studied with the protein kinase inhibitor H7. H7 (30–100 μm) produced no consistent effect on evoked or spontaneous ACh release. At these concentrations, however, H7 exerted an unfortunate inhibitory action on the nicotinic ACh receptor/ion channel.6H7 prevented the increases in spontaneous ACh release produced by CPT cyclic AMP (250 μm). Thus H7 is likely to inhibit PK A in frog motor nerve endings.7H7 did not alter the inhibitory effect of adenosine on evoked and spontaneous ACh release.8The results suggest: (i) that the adenylyl cyclase‐cyclic AMP‐PK A system is compartmentalized within the motor nerve terminal, (ii) that phosphorylation does not play a major role in ACh release and (iii) the cyclic AMP‐PK A system modulates rather than mediates the inhibitory effects of adenosine.