Takara H, Wada A, Arita M, Sumikawa K, Izumi F
Eur J Pharmacol. 1986 Jun 17;125(2):217-24. doi: 10.1016/0014-2999(86)90030-0.
The effects of ketamine, an intravenous anesthetic, on 22Na influx, 45Ca influx and catecholamine secretion were investigated in cultured bovine adrenal medullary cells. Ketamine inhibited carbachol-induced 45Ca influx and catecholamine secretion in a concentration-dependent manner with a similar potency (IC50 40 microM). Ketamine also reduced veratridine-induced 45Ca influx and catecholamine secretion (IC50 260 microM) but did not affect high K-induced 45Ca influx and catecholamine secretion. The influx of 22Na caused by carbachol or by veratridine was suppressed by ketamine with a concentration-inhibition curve similar to that of 45Ca influx and catecholamine secretion. Inhibition by ketamine of the carbachol-induced influx of 22Na, 45Ca and secretion of catecholamines was not reversed by the increased concentrations of carbachol. These observations indicate that ketamine, at clinical concentrations, can inhibit nicotinic receptor-associated ionic channels and that the inhibition of Na influx via the receptor-associated ionic channels is responsible for the inhibition of carbachol-induced Ca influx and catecholamine secretion. At higher concentrations, the anesthetic also inhibits voltage-dependent Na channels but has no effect on voltage-dependent Ca channels.
在培养的牛肾上腺髓质细胞中，研究了静脉麻醉剂氯胺酮对22Na内流、45Ca内流和儿茶酚胺分泌的影响。氯胺酮以浓度依赖的方式抑制卡巴胆碱诱导的45Ca内流和儿茶酚胺分泌，其效力相似（IC50为40 microM）。氯胺酮还降低了藜芦碱诱导的45Ca内流和儿茶酚胺分泌（IC50为260 microM），但不影响高钾诱导的45Ca内流和儿茶酚胺分泌。氯胺酮抑制了由卡巴胆碱或藜芦碱引起的22Na内流，其浓度抑制曲线与45Ca内流和儿茶酚胺分泌的相似。氯胺酮对卡巴胆碱诱导的22Na内流、45Ca内流和儿茶酚胺分泌的抑制作用不会因卡巴胆碱浓度的增加而逆转。这些观察结果表明，在临床浓度下，氯胺酮可以抑制烟碱受体相关的离子通道，并且通过受体相关离子通道对Na内流的抑制作用是抑制卡巴胆碱诱导的Ca内流和儿茶酚胺分泌的原因。在较高浓度下，该麻醉剂还抑制电压依赖性Na通道，但对电压依赖性Ca通道没有影响。
