Schimmel R J
Horm Metab Res. 1976 May;8(3):195-201. doi: 10.1055/s-0028-1093659.
Adipocytes were prepared by collagenase digestion of rat epididymal adipose tissue and incubated for 5, 15 or 30 minutes in Krebs-Ringer bicarbonate buffer containing albumin (40 mg/ml), glucose (1 mg/ml) and epinephrine. Calcium ion was present in some incubations at concentration of 2.5 mM and omitted from others; media with no added calcium contained 1.0 mM EGTA thereby producing a final calcium concentration of less than 10(-7) M. Glycerol release and accumulation of cyclic AMP were measured. Basal lipolysis and cell cyclic AMP levels were increased slightly but not significantly when adipocytes were incubated in calcium free media. Lipolysis could be activated with epinephrine in the absence of calcium but the sensitivity of the lipolytic response was greatly reduced; however, the maximum lipolytic response to epinephrine was not decreased in calcium free media. Similarly, incubation of adipocytes in calcium free media resulted in decreased accumulation of cyclic AMP in response to epinephrine but only when sub-maximum concentrations of the catecholamine were present. Varying the extracellular calcium concentration showed that a concentration of at least 10(-5) M was optimal for epinephrine activation of lipolysis. These observations are considered in accord with the view that activation of adenylate cyclase is facilitated by calcium ion.
通过胶原酶消化大鼠附睾脂肪组织制备脂肪细胞，并将其在含有白蛋白（40mg/ml）、葡萄糖（1mg/ml）和肾上腺素的Krebs-Ringer碳酸氢盐缓冲液中孵育5、15或30分钟。在一些孵育中存在浓度为2.5mM的钙离子，而在其他孵育中则省略；未添加钙的培养基含有1.0mM乙二醇双四乙酸（EGTA），从而产生最终钙浓度低于10^(-7)M。测量甘油释放和环磷酸腺苷（cAMP）的积累。当脂肪细胞在无钙培养基中孵育时，基础脂解和细胞cAMP水平略有升高但不显著。在无钙情况下，肾上腺素可激活脂解，但脂解反应的敏感性大大降低；然而，在无钙培养基中，对肾上腺素的最大脂解反应并未降低。同样，脂肪细胞在无钙培养基中孵育导致对肾上腺素反应时cAMP积累减少，但仅当存在亚最大浓度的儿茶酚胺时。改变细胞外钙浓度表明，至少10^(-5)M的浓度对于肾上腺素激活脂解是最佳的。这些观察结果被认为与钙离子促进腺苷酸环化酶激活的观点一致。
