Fig. 2. Cx37 and Cx43 levels are elevated in the medial layer of Cx40^–/– aorta. (A) Alkaline-extracted membranes from whole aortas of 6-7-week-old mice were immunoblotted. Membranes from the equivalent of 1.5 aortas are loaded in each lane. Cx37 levels slightly increased (1.4-fold) in Cx40^–/– aorta, after normalizing to PECAM. Cx43 levels increased fourfold in Cx40^–/– aorta. (B) SDS sample buffer lysates of aortic endothelium and alkaline-extracted membranes from medial-layer only preparations were immunoblotted (equivalent of 1.5 aortas per lane). Total endothelial Cx37 declined 8.2-fold in Cx40^–/– aorta, whereas medial Cx37 increased 4.4-fold. Cx43 also increased about fourfold in the medial layer of Cx40^–/– aorta. Cx40 was detected only in the endothelial fraction, as was PECAM. Cx43 was detected only in the medial layer preparation.