Mine T, Kojima I, Ogata E
Fourth Department of Internal Medicine, University of Tokyo School of Medicine, Japan.
Acta Endocrinol (Copenh). 1988 Oct;119(2):301-6. doi: 10.1530/acta.0.1190301.
Effects of glucagon on cytoplasmic concentration of free calcium, [Ca2+]c, were studied in aequorin-loaded hepatocytes. Addition of 5 nmol/l glucagon resulted in a prompt, but transient increase in aequorin bioluminescence. Glucagon, at 5 nmol/l, induced an increase in [Ca2+]c even in medium containing 1 mumol/l calcium, although the response was considerably smaller than that observed in medium containing 1.0 mmol/l calcium. When hepatocytes incubated in the presence of 1 mumol/l extracellular calcium were first stimulated by phenylephrine and subsequently by either glucagon or angiotensin II, there was a response of [Ca2+]c to glucagon, but not to angiotensin II. Dantrolene (50 mumol/l), which inhibits an increase in [Ca2+]c induced by phenylephrine, did not inhibit the increase in [Ca2+]c induced by glucagon. In contrast, dinitrophenol (50 mumol/l) abolished [Ca2+]c response to glucagon without abolishing the increase in [Ca2+]c induced by angiotensin II. These results suggest that glucagon mobilizes calcium from both intracellular and extracellular pools and that the intracellular calcium pool involved in glucagon action may be different from that mobilized by either phenylephrine or angiotensin II.
在水母发光蛋白负载的肝细胞中研究了胰高血糖素对游离钙细胞质浓度[Ca2+]c的影响。添加5 nmol/l的胰高血糖素导致水母发光蛋白生物发光迅速但短暂增加。即使在含有1 μmol/l钙的培养基中，5 nmol/l的胰高血糖素也会引起[Ca2+]c增加，尽管该反应比在含有1.0 mmol/l钙的培养基中观察到的反应小得多。当在含有1 μmol/l细胞外钙的情况下孵育的肝细胞首先用去氧肾上腺素刺激，随后用胰高血糖素或血管紧张素II刺激时，[Ca2+]c对胰高血糖素有反应，但对血管紧张素II没有反应。抑制去氧肾上腺素诱导的[Ca2+]c增加的丹曲林（50 μmol/l）并不抑制胰高血糖素诱导的[Ca2+]c增加。相反，二硝基苯酚（50 μmol/l）消除了[Ca2+]c对胰高血糖素的反应，而没有消除血管紧张素II诱导的[Ca2+]c增加。这些结果表明，胰高血糖素从细胞内和细胞外钙库中动员钙，并且参与胰高血糖素作用的细胞内钙库可能与去氧肾上腺素或血管紧张素II动员的钙库不同。
