Endothelin-1, delayed rectifier K channels, and pulmonary arterial smooth muscle

Sarafotoxin S6c [STXS6c; a selective endothelin-B (ETB) receptor agonist] causes constriction of isolated pulmonary arteries. In perforated-patch experiments on pulmonary arterial myocytes, ET-1 and STXS6c induced a gradual inhibition of the delayed rectifier K current (IKV), the profile of which resembled that carried by Kv1.5. Reverse-transcriptase polymerase chain reaction (RT-PCR) experiments revealed mRNA encoding this channel, and immunolocalization experiments demonstrated expression of the channel protein in pulmonary arterial smooth muscle. It is tempting to speculate that ETB receptor coupling to Kv1.5 may be implicated in contraction after stimulation of these receptors.