Nilsson K B, Andersson R G, Mohme-Lundholm E, Lundholm L
Acta Pharmacol Toxicol (Copenh). 1977 Jul;41(1):53-64. doi: 10.1111/j.1600-0773.1977.tb02123.x.
From a homogenate of rabbit colon muscle two ATP dependent Ca-accumulating microsomal fractions were isolated by differential centrifugation on a sucrose density grandient at 35% and 35-45% sucrose. Adenylate cyclase and phosphodiesterase activities were found in the fractions. The Ca-accumulation and the ATPase activity of these fractions were stimulated by cyclic AMP (10(-5)M) at an ATP concentration of 0.35 mM ATP. In the presence of higher concentrations of ATP (5 mM) cyclic AMP had no effect on the Ca-binding. The higher concentration of ATP markedly increased the cyclic AMP formation in relation to the activity found at the lower concentration of ATP. Isoprenaline (2 X 10(-6)M) stimulated the Ca-accumulation in the 35-45% fraction and increased the hydrolysis of ATP. These effects were absent in the fraction isolated at 35% sucrose. In the former fraction isoprenaline also stimulated the adenylate cyclase activity at 0.35 mM but not at 5 mM ATP. Both the effect of isoprenaline on the Ca-binding and the adenylate cyclase activity were inhibited by the adrenergic beta-receptor blocking agent sotalol. In the 35-45% fraction papaverine (1 X 10(-3)M) stimulated the Ca-accumulation and inhibited the phosphodiesterase activity. It is suggested that cyclic AMP and agents which influence the cyclic AMP metabolism in the microsomes may have a regulatory role on the Ca-binding of the microsomes.
通过在35%和35 - 45%蔗糖的蔗糖密度梯度上进行差速离心，从兔结肠肌肉匀浆中分离出两个依赖ATP的钙积累微粒体部分。在这些部分中发现了腺苷酸环化酶和磷酸二酯酶活性。在ATP浓度为0.35 mM时，环磷酸腺苷（10⁻⁵M）刺激了这些部分的钙积累和ATP酶活性。在较高浓度的ATP（5 mM）存在下，环磷酸腺苷对钙结合没有影响。较高浓度的ATP相对于较低浓度的ATP时发现的活性显著增加了环磷酸腺苷的形成。异丙肾上腺素（2×10⁻⁶M）刺激了35 - 45%部分的钙积累并增加了ATP的水解。在35%蔗糖分离的部分中没有这些作用。在前一个部分中，异丙肾上腺素在0.35 mM ATP时也刺激了腺苷酸环化酶活性，但在5 mM ATP时没有。异丙肾上腺素对钙结合和腺苷酸环化酶活性的作用都被肾上腺素β受体阻断剂索他洛尔抑制。在35 - 45%部分，罂粟碱（1×10⁻³M）刺激了钙积累并抑制了磷酸二酯酶活性。有人提出，环磷酸腺苷和影响微粒体中环磷酸腺苷代谢的物质可能对微粒体的钙结合具有调节作用。
