Ally A I, Horrobin D F, Karmali R A, Morgan R O, Karmazyn M, Manku M S
Prostaglandins. 1977 Jul;14(1):109-17. doi: 10.1016/0090-6980(77)90159-9.
Adenosine has actions on smooth muscle similar to those of prostaglandin (PG) antagonists. Like some PG antagonists it is a phosphodiesterase inhibitor and seems to interfere with calcium effects. It has agonist/antagonist interactions with theophylline, a PG antagonist. In rat mesenteric vascular smooth muscle adenosine blocked responses to noradrenaline which depend on release of intracellular calcium but not those to potassium ions which depend on calcium entry from extracellular fluid. Partial inhibition of endogenous PG synthesis by indomethacin enhanced the adenosine effect. In preparations in which vascular reactivity had been abolished by indomethacin and then partly restored by 1 or 5 ng/ml PG2, adenosine also inhibited responses to noradrenaline: the curve for the 5 ng/ml PG2 concentration was to the right of and parallel to the 1 ng/ml curve consistent with a competitive interaction between adenosine and PG2. Similar interactions between adenosine and PG2 were shown in human lymphocytes in which activation also depends on calcium release. These findings suggest how calcium-dependent metabolic responses may be controlled and indicate further reasons for caution in the interpretation of cyclic AMP experiments.
腺苷对平滑肌的作用类似于前列腺素（PG）拮抗剂。与某些PG拮抗剂一样，它是一种磷酸二酯酶抑制剂，似乎会干扰钙效应。它与PG拮抗剂茶碱存在激动剂/拮抗剂相互作用。在大鼠肠系膜血管平滑肌中，腺苷可阻断去甲肾上腺素依赖细胞内钙释放的反应，但不影响依赖细胞外液钙内流的钾离子反应。吲哚美辛对内源性PG合成的部分抑制增强了腺苷的作用。在血管反应性已被吲哚美辛消除、然后用1或5 ng/ml的PG2部分恢复的制剂中，腺苷也抑制对去甲肾上腺素的反应：5 ng/ml PG2浓度的曲线位于1 ng/ml曲线的右侧且与之平行，这与腺苷和PG2之间的竞争性相互作用一致。腺苷与PG2之间的类似相互作用也在人类淋巴细胞中得到体现，其中激活也依赖于钙释放。这些发现提示了钙依赖性代谢反应可能如何被控制，并指出了在解释环磷酸腺苷实验时需谨慎的进一步原因。
