Effect of pentobarbital on Na and Ca action potentials in an invertebrate neuron.
Effect of pentobarbital on Na and Ca action potentials in an invertebrate neuron.
复制标题
戊巴比妥对无脊椎动物神经元中 Na 和 Ca 动作电位的影响。
DOI：
10.1016/0006-8993(82)90222-0
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发表时间：
1982
期刊：
影响因子：
2.9
通讯作者：
Blaustein,MP
中科院分区：
文献类型：
--
作者：
Goldring,JM;Blaustein,MP
有人认为，钙电流可能是更敏感的巴比妥类药物封锁比钠电流。通过比较戊巴比妥（PB）对海兔腹神经节细胞R2中Ca依赖性和Na依赖性动作电位最大上升速率（Vdotmax）的影响，验证了这一假设。在无钙培养基（[Na]0= 494 mM）中，Na峰电位的Vdotmax范围为50 - 100 V/s，而在无钙培养基（[Ca]0= 30 mM）中，Ca峰电位的Vdotmax范围为7 - 20 V/s。在这些条件下，Ca-尖峰对巴比妥类药物阻断的敏感性是Na-尖峰的3-4倍。然而，发现Na-和Ca-峰对PB的敏感性取决于药物添加前峰的Vdotmax，Vdotmax通过改变载流阳离子上的驱动力来操纵，这通过改变浴介质中阳离子的浓度来实现。因此，Ca-尖峰，在含有10 mM Ca的介质中引起的，是更敏感的PB比在30 mM Ca引起的Ca-尖峰。同样，Na峰对PB的敏感性可以通过改变外部Na浓度来改变，从而改变Vdotmax。当调整外部Na和Ca浓度以使Na和Ca峰的Vdotmax相似时，在药物添加之前，Na和Ca峰的PB剂量-反应曲线重叠。PB敏感性依赖于药物添加前的Vdotmax的机制尚不清楚。然而，观察到当尖峰的Vdotmax相似时，Na和Ca尖峰的PB剂量-响应曲线相似，表明Na和Ca电流在该特定细胞中对PB可能同样敏感。
It has been suggested that Ca currents may be more sensitive to barbiturate blockade than Na currents. This hypothesis has been tested by comparing the effect of pentobarbital (PB) on the maximum rate of rise (Vdotmax) of Ca-dependent and Na-dependent action potentials in cell R2of theAplysiaabdominal ganglion. In Ca-free medium([Na]0= 494mM),Vdotmaxof Na-spikes ranged from 50 to 100 V/s, while in Na-free medium([Ca]0= 30mM),Vdotmaxof Ca-spikes ranged from 7 to 20 V/s. Under these conditions, Ca-spikes were 3–4 times more sensitive to barbiturate blockade than were Na-spikes. However, it was found that the sensitivity of Na- and Ca-spikes to PB depended onVdotmaxof the spike prior to drug addition.Vdotmaxwas manipulated by altering the driving force on the current carrying cation; this was accomplished by changing the concentration of the cation in the bathing medium. Thus, Ca-spikes, elicited in media containing 10 mM Ca, were more sensitive to PB than were Ca-spikes elicited in 30 mM Ca. Likewise, the sensitivity of Na-spikes to PB could be altered by changing the external Na concentration, and consequently,Vdotmax. When the external Na and Ca concentrations were adjusted so thatVdotmaxof Na- and Ca-spikes were similar, prior to drug addition, the PB dose-response curves for Na- and Ca-spikes overlapped. The mechanism accounting for the dependence of PB sensitivity onVdotmaxprior to drug addition remains unclear. However, the observation that PB dose-response curves for Na- and Ca-spikes are similar whenVdotmaxof the spikes is similar, suggests that Na and Ca currents may be equally sensitive to PB in this particular cell.