Pinto J E, Viglione P N, Kim M K
Arch Int Pharmacodyn Ther. 1985 Aug;276(2):236-46.
We examined the effect of hyperosmolality on exocytotic catecholamine secretion in isolated-perfused bovine adrenals, in both the absence and presence of Ca2+ in the extracellular medium. Exposure of adrenal glands to hyperosmotic media (600 mOsm/Kg H2O) for 20 minutes significantly decreased spontaneous catecholamine output, and was independent of extracellular Ca2+ concentration. Adrenal glands were exposed to a hyperosmotic Locke solution (600 mOsm/Kg H2O) for 10 minutes and then stimulated with acetylcholine. Hyperosmolality produced a significant, reversible inhibition of acetylcholine-evoked catecholamine secretion. As the osmotic strength of the perfusion fluid was increased, either by addition of sucrose or NaCl, there was a progressive reduction in the acetylcholine response. Hyperosmolality also decreased catecholamine release induced by 56 mM K+ and by removal of NaCl from the perfusion medium. Similar results were seen in glands exposed to a NaCl-free solution in the absence of extracellular Ca2+. These results suggest that inhibitory effects of hyperosmolality on stimulus-secretion coupling in the adrenal medulla are exerted after Ca2+ enters the chromaffin cells, and support one of the primary criteria of the chemiosmotic hypothesis.
我们研究了在细胞外培养基中存在和不存在Ca2+的情况下，高渗对离体灌注牛肾上腺中儿茶酚胺胞吐分泌的影响。将肾上腺暴露于高渗培养基（600 mOsm/Kg H2O）中20分钟，可显著降低儿茶酚胺的自发分泌量，且与细胞外Ca2+浓度无关。将肾上腺暴露于高渗洛克溶液（600 mOsm/Kg H2O）中10分钟，然后用乙酰胆碱刺激。高渗对乙酰胆碱诱发的儿茶酚胺分泌产生显著的、可逆的抑制作用。随着灌注液渗透压的增加，无论是通过添加蔗糖还是氯化钠，乙酰胆碱反应都逐渐降低。高渗还减少了由56 mM K+和从灌注培养基中去除氯化钠诱导的儿茶酚胺释放。在没有细胞外Ca2+的情况下，暴露于无氯化钠溶液的腺体中也观察到了类似的结果。这些结果表明，高渗对肾上腺髓质刺激-分泌偶联的抑制作用是在Ca2+进入嗜铬细胞后发挥的，支持了化学渗透假说的主要标准之一。
