Ryanodine-sensitive, thapsigargin-insensitive calcium uptake in rat ventricle homogenates
Ryanodine-sensitive, thapsigargin-insensitive calcium uptake in rat ventricle homogenates
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大鼠心室匀浆中兰尼定敏感、毒胡萝卜素不敏感的钙摄取
DOI：
10.1023/a:1006800328118
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发表时间：
1998
影响因子：
4.3
通讯作者：
Q. Wu
中科院分区：
文献类型：
--
作者：
J. Feher;Keom Nam Lee;Q. Wu
Thapsigargin是一种天然产物，具有高亲和力，可特异性抑制所有已知的SERCA钙泵。我们通过测量未分离的匀浆和分离的SR部分中草酸盐支持的钙摄取率来研究thapsigargin对心肌肌浆网（SR）的影响。在分离的SR和未分离的匀浆中，高浓度的ryanodine预孵育会使SR的吸收速率提高两倍，从而关闭SR的流出通道。无论是否存在SR通道阻断，Thapsigargin都能从化学计量上完全抑制离体SR的钙摄取速率。相比之下，只有在没有SR通道阻断的情况下，thapsigargin几乎完全抑制了匀浆钙的摄取；在存在阻断的情况下，约20%的摄取活性对信号素不敏感。这一结果揭示了心脏中钙摄取的一种素不敏感、红嘌呤敏感的成分。这种活性存在于草酸渗透池中，并被环吡唑酸（SERCA钙泵的另一种抑制剂）抑制。大鼠EDL肌肉匀浆中无tg不敏感活性。在分离的SR中，缺乏thapsigargin不敏感摄取活性可能是由于SR在分离过程中失活所致。草酸盐的渗透性和ryanodine的敏感性表明tg不敏感钙摄取活性与经典SR密切相关。thapsigargin敏感性的不同表明心脏中存在两种细胞内钙泵。
Thapsigargin is a natural product that specifically inhibits all known SERCA calcium pumps with high affinity. We investigated the effects of thapsigargin on cardiac sarcoplasmic reticulum (SR) by measuring the oxalate-supported calcium uptake rate in the unfractionated homogenate and in the isolated SR fraction. The uptake rate in both the isolated SR and unfractionated homogenate are stimulated about two-fold by preincubation with high concentrations of ryanodine, which closes the SR efflux channel. Thapsigargin stoichiometrically and completely inhibited the calcium uptake rate in the isolated SR, both in the presence and absence of SR channel blockade. In contrast, thapsigargin nearly completely inhibited the homogenate calcium uptake only in the absence of SR channel blockade; in the presence of blockade, about 20% of the uptake activity was insensitive to thapsigargin. This result unmasks a thapsigargin-insensitive, ryanodine-sensitive component of calcium uptake in the heart. This activity is in an oxalate-permeable pool and is inhibited by cyclopiazonic acid, another inhibitor of the SERCA calcium pumps. There was no TG-insensitive activity in the rat EDL muscle homogenate. The absence of thapsigargin-insensitive uptake activity in the isolated SR can be attributed to its inactivation during the isolation of the SR. The oxalate permeability and ryanodine sensitivity suggest that the TG-insensitive calcium uptake activity is closely related to the classical SR. The different thapsigargin sensitivities suggests the existence of two kinds of intracellular calcium pumps in the heart.
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大鼠大脑微粒体膜的生化和功能异质性与 SERCA Ca(2)-ATP 酶和 Ca2 释放通道相关。
影响因子：
4
作者：
Nori,A;Fulceri,R;Gamberucci,A;Benedetti,A;Volpe,P
通讯作者：
Volpe,P
DOI：
--
发表时间：
1986-05
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
G. Meissner
通讯作者：
G. Meissner
DOI：
10.1016/s0021-9258(19)47340-7
发表时间：
1991-09
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Jonathan LyttonSg;Marisa WestlinS;Michael R. Hanleyll
通讯作者：
Jonathan LyttonSg;Marisa WestlinS;Michael R. Hanleyll
DOI：
10.1172/jci118197
发表时间：
1995-09
期刊：
The Journal of clinical investigation
影响因子：
--
作者：
M. Zaidi;V. Shankar;R. Tunwell;O. Adebanjo;J. Mackrill;M. Pazianas;D. O'Connell;B. Simon;B. Rifkin;A. Venkitaraman
通讯作者：
M. Zaidi;V. Shankar;R. Tunwell;O. Adebanjo;J. Mackrill;M. Pazianas;D. O'Connell;B. Simon;B. Rifkin;A. Venkitaraman
DOI：
10.1016/0005-2736(87)90336-1
发表时间：
1987
期刊：
Biochimica et biophysica acta
影响因子：
--
作者：
Alderson,BH;Feher,JJ
通讯作者：
Feher,JJ