Kopach O V, Kruhlykov I A, Voĭtenko N V, Fedirko N V
Fiziol Zh (1994). 2005;51(1):62-71.
Acinar cells of rat submandibular salivary gland are characterized by heterogeneity of intracellular Ca2+ stores. In the present work we have studied this heterogeneity using Arsenazo III dye to measure a cellular total calcium content and Fura-2/AM, to determine free cytosolic calcium concentration ([Ca2+]i). We have found that the amount of Ca2+ released by inhibition of Ca2+ ATPase of the ER with thapsigargin comprises approximately 30% of total ER calcium. This result was obtained in experiments on both intact and permeabilized acinar cells. We have also shown that both Ca2+ ATPase inhibition with thapsigargin and emptying the stores with acetylcholine (ACh) led to activation of store-operated Ca2+ influx (an increase in total calcium content of approximately 14%). In permeabilized cells application of ACh after preincubation with thapsigargin led to a further decrease in total cellular calcium content (approximately 38%). At the same time in intact cells it resulted in generation of [Ca2+]i transients with gradually decreasing amplitudes. Thus, ACh is capable of producing an additional release of Ca2+ from thapsigargin-insensitive stores. This additional release is IP3-dependent since it was completely blocked by heparin. We conclude that in acinar cells of rat submandibular gland thapsigargin-sensitive and thapsigargin-insensitive Ca2+ stores could exist.
大鼠下颌下唾液腺的腺泡细胞具有细胞内钙储存异质性的特征。在本研究中，我们使用偶氮胂III染料测量细胞总钙含量，并使用Fura-2/AM测定游离胞质钙浓度（[Ca2+]i），以此来研究这种异质性。我们发现，用毒胡萝卜素抑制内质网的Ca2+ ATP酶所释放的Ca2+量约占内质网总钙量的30%。这一结果是在完整和透化的腺泡细胞实验中获得的。我们还表明，用毒胡萝卜素抑制Ca2+ ATP酶以及用乙酰胆碱（ACh）排空储存都导致了储存操纵性Ca2+内流的激活（总钙含量增加约14%）。在透化细胞中，先用毒胡萝卜素预孵育后再施加ACh会导致细胞总钙含量进一步降低（约38%）。与此同时，在完整细胞中，它会导致[Ca2+]i瞬变的产生，且幅度逐渐减小。因此，ACh能够从毒胡萝卜素不敏感的储存中额外释放Ca2+。这种额外释放是依赖肌醇三磷酸（IP3）的，因为它被肝素完全阻断。我们得出结论，在大鼠下颌下腺的腺泡细胞中可能存在毒胡萝卜素敏感和毒胡萝卜素不敏感的Ca2+储存。
