Angiotensin II Ca2+ signaling in rat afferent arterioles:: stimulation of cyclic ADP ribose and IP3 pathways
Angiotensin II Ca2+ signaling in rat afferent arterioles:: stimulation of cyclic ADP ribose and IP3 pathways
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DOI：
10.1152/ajprenal.00372.2004
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发表时间：
2005-04-01
影响因子：
4.2
通讯作者：
Arendshorst, WJ
中科院分区：
文献类型：
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作者：
Fellner, SK;Arendshorst, WJ
ANG II通过肌醇三磷酸受体（IP3R）的激活和肌浆网（SR） Ca2+的释放诱导血管平滑肌（VSM）细胞内胞浆Ca2+ ([Ca2+](i))的升高。钙诱导钙释放（CICR）和环腺二磷酸核糖（cADPR）增强Ca2+信号，使红嘌呤敏感受体（RyR）对Ca2+敏感，进一步增强CICR。cADPR是由β -烟酰胺腺嘌呤二核苷酸（NAD(+)）通过膜结合双功能酶ADPR环化酶合成的。为了研究ANG II激活传入小动脉ADPR环化酶的可能性，我们使用了IP3R、RyR和ADPR环化酶的抑制剂。用磁化微球和筛分技术分离大鼠肾传入小动脉，负载fura-2测定[Ca2+](i)。在含Ca2+缓冲液中，ANG II使[Ca2+](i)增加125 +/- 10 nM。在IP3R拮抗剂TMB-8和2-APB存在的情况下，对ANG II的峰值反应分别降低了74%和81%。cADPR的特异性拮抗剂8-Br ADPR和高浓度的ryanodine （100 muM）对ANG ii诱导的[Ca2+](i)的增加分别抑制了75%和69%。烟酰胺和Zn2+是已知的VSM ADPR环化酶抑制剂。烟酰胺使[Ca2+](i)对ANGⅱ的反应降低66%。在无钙缓冲液中，Zn2+降低了68%的ANG II反应。同时阻断IP3和cADPR通路可使[Ca2+](i)对ANG II的反应降低83%。我们得出结论，ANG II通过经典的IP3R途径在传入小动脉中启动SR中的Ca2+动员，并且ANG II可能导致ADPR环化酶的激活形成cADPR， cADPR通过其对RyR的作用，大大增强了Ca2+反应。
ANG II induces a rise in cytosolic Ca2+ ([Ca2+](i)) in vascular smooth muscle (VSM) cells via inositol trisphosphate receptor (IP3R) activation and release of Ca2+ from the sarcoplasmic reticulum (SR). The Ca2+ signal is augmented by calcium-induced calcium release (CICR) and by cyclic adeninediphosphate ribose (cADPR), which sensitizes the ryanodine-sensitive receptor (RyR) to Ca2+ to further amplify CICR. cADPR is synthesized from beta-nicotinamide adenine dinucleotide (NAD(+)) by a membrane-bound bifunctional enzyme, ADPR cyclase. To investigate the possibility that ANG II activates the ADPR cyclase of afferent arterioles, we used inhibitors of the IP3R, RyR, and ADPR cyclase. Afferent arterioles were isolated from rat kidney with the magnetized microsphere and sieving technique and loaded with fura-2 to measure [Ca2+](i). In Ca2+-containing buffer, ANG II increased [Ca2+](i) by 125 +/- 10 nM. In the presence of the IP3R antagonists TMB-8 and 2-APB, the peak responses to ANG II were reduced by 74 and 81%, respectively. The specific antagonist of cADPR 8-Br ADPR and a high concentration of ryanodine (100 muM) inhibited the ANG II-induced increases in [Ca2+](i) by 75 and 69%, respectively. Nicotinamide and Zn2+ are known inhibitors of the VSM ADPR cyclase. Nicotinamide diminished the [Ca2+](i) response to ANG II by 66%. In calcium-free buffer, Zn2+ reduced the ANG II response by 68%. Simultaneous blockade of the IP3 and cADPR pathways diminished the [Ca2+](i) response to ANG II by 83%. We conclude that ANG II initiates Ca2+ mobilization from the SR in afferent arterioles via the classic IP3R pathway and that ANG II may lead to activation of the ADPR cyclase to form cADPR, which, via its action on the RyR, substantially augments the Ca2+ response.