Clementi E, Scheer H, Raichman M, Meldolesi J
Department of Pharmacology, CNR Center of Cytopharmacology, University of Milano, Italy.
Biochem Biophys Res Commun. 1992 Nov 16;188(3):1184-90. doi: 10.1016/0006-291x(92)91356-u.
A PC12 cell clone that responds to ATP with polyphosphoinositide hydrolysis and with a marked, biphasic intracellular free Ca2+ concentration ([Ca2+]i) response (composed by release from intracellular stores accompanied by stimulated influx from the medium), was pretreated with pertussis toxin. In the pretreated cells the responses induced by ATP were differently modified. Polyphosphoinositide hydrolysis and Ca2+ release were moderately inhibited whereas Ca2+ influx was enhanced. Pharmacological experiments revealed the influx enhancement to be sustained by neither voltage-gated nor second messenger-operated Ca2+ channels. Rather, a channel of the receptor-operated type activated by ATP (P2w receptor) appears to work under the negative control of a pertussis toxin-sensitive G protein, acting presumably by direct interaction with the channel in the plane of the plasma membrane.
一个对ATP产生多磷酸肌醇水解反应，并伴有显著双相细胞内游离钙离子浓度（[Ca2+]i）反应（由细胞内储存库释放并伴有来自培养基的刺激流入组成）的PC12细胞克隆，用百日咳毒素进行预处理。在预处理的细胞中，ATP诱导的反应有不同程度的改变。多磷酸肌醇水解和Ca2+释放受到中度抑制，而Ca2+流入增强。药理学实验表明，流入增强既不是由电压门控的Ca2+通道维持，也不是由第二信使操作的Ca2+通道维持。相反，由ATP激活的受体操作型通道（P2w受体）似乎在百日咳毒素敏感的G蛋白的负调控下起作用，可能是通过在质膜平面上与通道直接相互作用来实现的。
