Expression and Function of Endothelial Ca 2+ -Activated K + Channels in Human Mesenteric Artery

Abstract

—Ca2+-activated K+ (KCa) channels have been suggested to play a role in the control of endothelial functions such as regulation of vascular tone and cell proliferation. We established a method for single-cell reverse transcriptase–polymerase chain reaction analysis in combination with the patch-clamp technique to characterize KCa channel expression and function in single endothelial cells (ECs) within the endothelial monolayer of intact human mesenteric arteries (MAs) and in disease states. We tested whether endothelial KCa channel expression and function are altered in MAs obtained from patients with colonic adenocarcinoma (CA) compared with those in MAs from non–cancer patients with inactive diverticulitis. Expression of the intermediate-conductance KCa channel (hIK1) was detected in non–cancer and CA patients. In whole-cell patch-clamp measurements, only ECs expressing hIK1 exhibited corresponding KCa currents, whereas respective KCa currents were missing in hIK1-negative ECs. This heterogeneit...