Tamarit-Rodriguez J
Acta Physiol Scand. 1978 Aug;103(4):379-83. doi: 10.1111/j.1748-1716.1978.tb06231.x.
Fluxes of 45Ca2+ were studied in beta-cell rich islets of non-inbred ob/ob-mice, using LaCl3 to wash out extra-cellular and superficially bound 45Ca2+. The ionophore A-23187 (10 microM) increased the 45Ca2+ uptake in islets both at 3 and 20 mM D-glucose, the effect being more pronounced after 10 min than after 120 min of incubation. In incubations for 120 min, 20 mM D-glucose induced a higher uptake of 45Ca2+ than did A-23187. The ionophore enhanced the unidirectional efflux of 45Ca2+ from preloaded islets. Pretreatment of islets with 20 mM D-glucose in non-radioactive medium inhibited the subsequent D-glucose-induced 45Ca2+ uptake. Similar pretreatment with A-23187 increased the subsequent ionophore-induced 45Ca2+ uptake. The results suggest that A-23187 acts by catalyzing Ca2+ fluxes across the beta-cell plasma membrane. The different effects of D-glucose and A-23187 on 45Ca2+ fluxes suggest that the two agents act through different mechanisms in the beta-cells.
利用LaCl₃洗去细胞外及表面结合的⁴⁵Ca²⁺，研究了非近交ob/ob小鼠富含β细胞的胰岛中⁴⁵Ca²⁺的通量。离子载体A - 23187（10微摩尔）在3毫摩尔和20毫摩尔D - 葡萄糖条件下均增加了胰岛对⁴⁵Ca²⁺的摄取，孵育10分钟后的效果比孵育120分钟后更明显。在孵育120分钟时，20毫摩尔D - 葡萄糖诱导的⁴⁵Ca²⁺摄取高于A - 23187。该离子载体增强了预加载胰岛中⁴⁵Ca²⁺的单向流出。在非放射性培养基中用20毫摩尔D - 葡萄糖预处理胰岛可抑制随后D - 葡萄糖诱导的⁴⁵Ca²⁺摄取。用A - 23187进行类似的预处理则增加了随后离子载体诱导的⁴⁵Ca²⁺摄取。结果表明，A - 23187通过催化Ca²⁺跨β细胞质膜的通量起作用。D - 葡萄糖和A - 23187对⁴⁵Ca²⁺通量的不同影响表明，这两种试剂在β细胞中通过不同机制起作用。
