Endothelial Cells Freshly Isolated from Resistance-Sized Pulmonary Arteries Possess a Unique K+ Current Profile

Abstract We have, for the first time, developed a reliable method for freshly isolating viable endothelial cells from resistance-sized rat pulmonary arteries. The endothelial origin of these cells was confirmed using indirect immunofluorescence, utilizing fluorescently labeled low-density lipoprotein. Biophysical and pharmacological patch-clamp experiments conducted under quasiphysiological cationic gradients revealed that these cells had a mean resting membrane potential of ∼−38 mV and displayed a delayed-rectifying K + current. Immunohistochemical staining of rat lung cross-sections revealed an abundance of K V 1.5 channel protein in pulmonary endothelium. This is the first report of a delayed-rectifying K + current in endothelial cells of resistance-sized pulmonary arteries. Since changes in membrane potential associated with K + channel activity affect release of vasoactive substances from endothelial cells, this finding has important implications for understanding the mechanisms underlying control of pulmonary vascular tone.