Background:

Tetraethylammonium chloride (TEAC) is a quaternary ammonium compound, which has been used as the source of tetraethylammonium ions in pharmacological and physiological studies.

In vitro: Tetraethylammonium (TEA) is a small ion that is thought to block open K channels by binding either to an internal or to an external site. For this reason, it has been used to probe the ion conduction pathway or pore of K channel mutants and a K channel chimera. TEA blocks K+ channels at two sites, which define the inner and outer mouths of the channel pores [1].

In vivo: Vasorelaxant effect of taurine can be diminished by TEA in rat isolated arteries [2]

Clinical trial: TEAC blocks both sympathetic and parasympathetic transmission at the ganglia. TEAC can relieve the pain of coronary artery disease. By the use of TEAC, the symptoms of Buerger's disease seem to be meliorated, at least temporarily. TEAC appears to be of little value in advanced arteriosclerotic diseases [3].

参考文献:
[1] Taglialatela M, Vandongen AM, Drewe JA, Joho RH, Brown AM, Kirsch GE.  Patterns of internal and external tetraethylammonium block in four homologous K+ channels. Mol Pharmacol. 1991 Aug;40(2):299-307.
[2] Niu LG, Zhang MS, Liu Y, Xue WX, Liu DB, Zhang J, Liang YQ.  Vasorelaxant effect of taurine is diminished by tetraethylammonium in rat isolated arteries. Eur J Pharmacol. 2008 Feb 2;580(1-2):169-74. Epub 2007 Oct 25.
[3] SHEA PA, DUNKLEE PE, et al.  Preliminary clinical investigation of tetraethylammonium chloride with particular reference to disorders of the circulatory system. Calif Med. 1948 Sep;69(3):193-6.