High-resolution scanning patch clamp: life on the nanosurface.
High-resolution scanning patch clamp: life on the nanosurface.
复制标题
高分辨率扫描膜片钳：纳米表面上的生命。
DOI：
10.1161/circresaha.113.301212
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发表时间：
2013
影响因子：
20.1
通讯作者：
Robertson,GailA
中科院分区：
文献类型：
--
作者：
Robertson,GailA
at sites where local currents must be amplified into action potentials with a high safety factor—the axonal initial segment, 10, 11 the node of Ranvier, 12 and the perimeter of the neuromuscular junction end plate. 13 Considering that a single action potential must trigger tightly synchronous excitation–contraction coupling throughout the cardiomyocyte, 14 a high safety factor seems like a good idea as the action potential propagates from the surface sarcolemma into the belly of the muscle along the T-tubule. It has been shown that the T-tubules present a barrier to diffusion, such that high levels of activity or in some disease states might cause an accumulation of potassium within their confined space. 15 A resulting local depolarization of the T-tubular membrane would be expected to increase steady-state Na channel inactivation and thereby reduce Na channel availability. The clusters of Na channels on the crest could serve to amplify the sarcolemmal signal and safeguard against action potential failure under such changing conditions. Whatever the role of these clustered channels, their discovery demonstrates new clarity of structure linked to function not realized with other techniques. As with any technique that is more than just a gearhead’s brainchild, ideas for new applications abound. Perhaps super-resolution scanning patch clamp could detect smaller domains as they are called into action. Membrane caveolae comprise a host of proteins involved in signaling, exemplified by the dependence of β-adrenergic modulation of L-type Ca channels on caveolin-3. 16 In these dynamic membrane compartments, the larger scanning ion conductance microscopy probe might provide new insights into mechanisms underlying an increased activity in response to sympathetic stimulation. Similarly, the technique could capture the recruitment of ion channel reserves such as the covert population of TTX-sensitive channels uncovered by scorpion toxin7 or the channels producing IKs, upregulated by sympathetic activation to protect against QT prolongation and sudden cardiac death. 17, 18 And what about ion transporters, the function of which is equally amenable to probing with a patch pipette? Will this approach uncover functional coupling with neighboring ion channels, where their activity would establish a gradient with nanoscale dimensions?Finally, let us consider the potential for super-resolution scanning patch clamp in assessing disease-induced structural and functional changes. Under conditions of heart failure and ischemic heart disease, T-tubule organization is disrupted. 19–21 Ion channels normally tethered by scaffolding proteins to T-tubules are concomitantly perturbed. But T-tubule perturbation can happen early in disease processes that presage overt signs of heart failure or arrhythmia. 22 Could this new technique help define the changes in ion channel distribution or dyad coupling that follow detubulation, providing possible targets for therapeutic intervention to delay the onset of disease? Will channel clusters disperse as a substrate for dyssynchrony of Ca release or be resorbed, shifting the balance of currents and reducing the efficacy of conduction? With an inverted microscope, a piezo-electric controller, and the software developed as part of the study, this approach will enable many of us to climb down from our perches at 30 000 ft to peer into the nanoscale nooks and crannies of the cell surface
