Similarly to the findings from the study examining pial artery function in the J20 mouse model of AD (15), we observed a reduction in pial artery endothelial Kir2.1 function, as evidenced by compromised dilation of resistance arteries in response to external K+ together with a decrease in Kir2.1 current density in the ECs of these arteries. The gene discussed is KCNJ2; the disease is Alzheimer disease.