Figure 1. Freshly isolated endothelial cells (ECs), but not smooth muscle cells (SMCs) exhibit functional inward rectifier potassium (Kir) channels in third‐order mesenteric arteries .

The Kir currents were recorded using the perforated patch configuration of the patch‐clamp technique. A, representative current traces in the SMCs from third‐order mesenteric arteries. There was no difference between the inward currents at −140 mV before and after addition of Ba²⁺ in the SMCs (n = 7 SMCs; P = 0.2035 using Student's t test). B and C, representative current traces in ECs from third‐order mesenteric arteries in the presence and absence of Ba²⁺ (100 μm) at extracellular K⁺ concentrations of 6 (B) and 60 mm (C). The cells were held at −50 mV, and 400 ms ramps from −140 to +50 mV were applied. The [K⁺]_in was 140 mm. Kir current was estimated as the decrease in current following the addition of Ba²⁺. D, continuous current recordings at physiological membrane potential (−50 mV) in EC and SMCs, starting at 6 mm K⁺ physiological saline solution (PSS). E, representative traces for ML‐133‐sensitive Kir currents in the ECs. F, a bar graph showing averaged Kir current densities using Ba²⁺ and ML‐133 in the ECs (n = 10 cells for Ba²⁺ and n = 5 ECs for ML‐133; P = 0.4931 using Student's unpaired t test).