Maisel A S, Motulsky H J
Clin Pharmacol Ther. 1987 Jul;42(1):100-6. doi: 10.1038/clpt.1987.115.
Mononuclear leukocytes are easily accessible cells for investigating the regulation of beta-adrenergic receptors in humans. We have previously shown that brief incubations with agonists redistribute (? internalize) most of the beta-adrenergic receptors on mononuclear leukocytes away from the cell surface without changing total receptor number. However, negligible redistribution occurred after exercise or an infusion of isoproterenol. The current study was designed to ask whether receptor redistribution occurs over a longer time course after administration of terbutaline, a beta 2-adrenergic agonist that is known to cause a decrease in receptor number. Normal volunteers were given terbutaline, 5 mg t.i.d. for 6 days. As expected, the number of beta-adrenergic receptors decreased. However, the remaining receptors were not redistributed. Redistribution also did not occur after 1 or 2 days of terbutaline, at which time down regulation was minimal. We also found that terbutaline did not alter the ability of the receptors to be redistributed or desensitized by a preincubation with isoproterenol.
单核白细胞是研究人类β-肾上腺素能受体调节的易于获取的细胞。我们之前已经表明，与激动剂短暂孵育会使单核白细胞上的大多数β-肾上腺素能受体从细胞表面重新分布（内化），而不改变总受体数量。然而，运动或输注异丙肾上腺素后几乎没有发生重新分布。当前的研究旨在探讨在给予特布他林（一种已知会导致受体数量减少的β2-肾上腺素能激动剂）后，受体重新分布是否会在更长的时间过程中发生。正常志愿者服用特布他林，每日3次，每次5mg，共6天。正如预期的那样，β-肾上腺素能受体的数量减少了。然而，剩余的受体并未重新分布。在给予特布他林1天或2天后也未发生重新分布，此时下调作用最小。我们还发现，特布他林不会改变受体通过与异丙肾上腺素预孵育而重新分布或脱敏的能力。
