Stimulation of unitary T-type Ca2+ channel currents by calmodulin-dependent protein kinase II
Stimulation of unitary T-type Ca2+ channel currents by calmodulin-dependent protein kinase II
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DOI：
10.1152/ajpcell.2000.279.6.c1694
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发表时间：
2000-12-01
影响因子：
5.5
通讯作者：
Pancrazio, JJ
中科院分区：
文献类型：
--
作者：
Barrett, PQ;Lu, HK;Pancrazio, JJ
用膜片钳技术观察了钙/钙调素依赖性蛋白激酶II（CaMK II）对牛肾上腺肾小球（AG）细胞单一低电压激活（LVA）T型钙通道电流的影响。在细胞贴附和由内而外的贴片中，通过电压依赖性失活和在110 mM BaCl 2或CaCl 2中类似于9 pS的单通道电导来鉴定LVA通道活性。在细胞贴附贴片中，浴Ca 2+从150 nM升高至1 μ M，提高了K+去极化（140 mM）细胞中的细胞内Ca 2+，并引起LVA Ca 2+通道开放概率（NPo）增加2至6倍。这种增强与非空白扫描次数的增加、非空白扫描中通道开放频率的上升以及首次潜伏期减少30%有关。单通道开放时间分布、爆发长度或开放/爆发无明显变化。AG细胞与亲脂性或肽抑制剂的CaMKII在细胞附着或切除（内-外）配置预孵育防止引起的升高的钙离子浓度升高的NPO的上升。此外，在缺乏升高的Ca 2+的情况下，施用表现出辅因子非依赖性活性的突变体重组CaMKII α在LVA通道NPo中产生三倍升高。这些数据表明，CaMKII活性是必要的和足够的LVA通道激活的Ca 2+。
The effect of Ca2+/calmodulin-dependent protein kinase II (CaMKII) stimulation on unitary low voltage-activated (LVA) T-type Ca2+ channel currents in isolated bovine adrenal glomerulosa (AG) cells was measured using the patch-clamp technique. In cell-attached and inside-out patches, LVA channel activity was identified by voltage-dependent inactivation and a single-channel conductance of similar to9 pS in 110 mM BaCl2 or CaCl2. In the cell-attached patch, elevation of bath Ca2+ from 150 nM to 1 muM raised intracellular Ca2+ in K+-depolarized (140 mM) cells and evoked an increase in the LVA Ca2+ channel probability of opening (NPo) by two-to sixfold. This augmentation was associated with an increase in the number of nonblank sweeps, a rise in the frequency of channel opening in nonblank sweeps, and a 30% reduction in first latency. No apparent changes in the single-channel open-time distribution, burst lengths, or openings/burst were apparent. Preincubation of AG cells with lipophilic or peptide inhibitors of CaMKII in the cell-attached or excised (inside-out) configurations prevented the rise in NPo elicited by elevated Ca2+ concentration. Furthermore, administration of a mutant recombinant CaMKII alpha exhibiting cofactor-independent activity in the absence of elevated Ca2+ produced a threefold elevation in LVA channel NPo. These data indicate that CaMKII activity is both necessary and sufficient for LVA channel activation by Ca2+.