Svoboda P, Teisinger J, Vyskocil F
Comp Biochem Physiol C Comp Pharmacol Toxicol. 1986;84(2):283-90. doi: 10.1016/0742-8413(86)90095-2.
Catecholamines stimulate Na,K-ATPase activity in the microsomal membranes of the brain and brown adipose tissue. This stimulation is apparent in the absence of soluble, cytosolic inhibitors and exhibits the same characteristics in both tissues: it occurs at high concentrations (10(-6)-10(-4) M) only; there is no difference in potency between isoprenaline, norepinephrine and epinephrine (EC50 = 1-2 X 10(-5) M); the D-stereoisomer of isoprenaline is equally as effective as the L-form; stimulation of Na,K-ATPase may also be achieved by the metal chelators EDTA, EGTA and desferal; the hydrophobic beta-blockers, propranolol and alprenolol, inhibit both the norepinephrine-stimulated and basal levels of enzyme activity at concentrations of 10(-5)-10(-3) M; phenoxybenzamine, an irreversible alpha-adrenergic blocker, inhibits basal Na,K-ATPase as well as norepinephrine-stimulated enzyme activity (EC50 = 2.5 X 10(-5) M). Because none of these observations can be related to the properties of the stereospecific adrenergic receptor (alpha or beta), it may be concluded that the catecholamine-Na,K-ATPase interaction is not mediated by the receptor. More probably, catecholamines may antagonize the Na,K-ATPase inhibition caused by some tightly membrane-bound metals (but not vanadium) via the ortho-catechol moiety of the catecholamine molecule. The stimulation of brown fat Na,K-ATPase by catecholamines does not have much relevance to the norepinephrine-stimulated thermogenesis in this tissue.
儿茶酚胺可刺激大脑和棕色脂肪组织微粒体膜中的钠钾 - ATP酶活性。这种刺激在没有可溶性胞质抑制剂的情况下很明显，并且在两种组织中表现出相同的特征：仅在高浓度（10^(-6)-10^(-4) M）时发生；异丙肾上腺素、去甲肾上腺素和肾上腺素之间的效力没有差异（EC50 = 1 - 2×10^(-5) M）；异丙肾上腺素的D - 立体异构体与L - 形式同样有效；金属螯合剂乙二胺四乙酸（EDTA）、乙二醇双乙醚二胺四乙酸（EGTA）和去铁胺也可刺激钠钾 - ATP酶；疏水性β受体阻滞剂普萘洛尔和阿普洛尔在浓度为10^(-5)-10^(-3) M时可抑制去甲肾上腺素刺激的酶活性以及基础酶活性水平；苯氧苄胺是一种不可逆的α肾上腺素能阻滞剂，可抑制基础钠钾 - ATP酶以及去甲肾上腺素刺激的酶活性（EC50 = 2.5×10^(-5) M）。由于这些观察结果均与立体特异性肾上腺素能受体（α或β）的特性无关，因此可以得出结论，儿茶酚胺与钠钾 - ATP酶的相互作用不是由受体介导的。更有可能的是，儿茶酚胺可能通过儿茶酚胺分子的邻苯二酚部分拮抗由某些紧密结合在膜上的金属（但不是钒）引起的钠钾 - ATP酶抑制。儿茶酚胺对棕色脂肪钠钾 - ATP酶的刺激与该组织中去甲肾上腺素刺激的产热没有太大关系。
