钾通道开放剂拮抗4－氨基吡啶诱发大鼠肥大细胞释放组胺

POTASSIUM CHANNEL OPENERS ANTAGONIZE4-AMINOPYRIDINE INDUCED HISTAMINE RELEASE FROM RAT PERITONEAL MAST CELLS

４－氨基吡啶（４－ＡＰ）能诱发大鼠腹腔肥大细胞（ＰＭＣ）释放组胺，且呈浓度依赖关系。钾通道开放剂二氮嗪（Ｄｉａ），米诺地尔（Ｍｉｎ）及钙拮抗剂硝苯啶（Ｎｉｆ）均能明显抑制４－ＡＰ诱发大鼠ＰＭＣ释放组胺。实验结果提示，大鼠肥大细胞膜上可能存在钾通道，４－ＡＰ可能通过阻滞钾通道，使钙通道开放，Ｃａ２＋内流增加而促进组胺释放，钾通道开放剂可能是一类新的组胺释放拮抗剂。

AMinopyridine (4-AP)was shown to promote histamine release from isolatedrat peritoneal mast cells(PMC )in a dose-dependent manner.Potassium channel openers ,minoxidil(Min)200 mg·kg-1 ig,diazoxide(Dia) 500 μmol·L-1 in vitro and calcium antagonist nifedipine(Nif)125 mg· kg-1 ig were found to inhibit 4-AP induced histamine release from rat PMC. Electronmicroscopy revealed that 4-AP caused partial degranulation of PMC and extrusion of granules and Min200 mg· kg-1 ig retarded this phenomenon. These results provide evidence that potassium channelsare present in rat mast cell membrane and indicate that the mechanism of histamine release by 4-APmay be related to its potassium channel blocking effect. As a result of this effect, the calcium channelsopen and Ca2+ influx to the mast cells increases,thus eliciting histamine release. Potassium channelopeners seemed to be a new group of inhibitors of histamine release from mast cells.