Fig. 1

Primary elephant seal arterial endothelial cells express canonical endothelial markers and modulate cellular respiration in response to hypoxia/reoxygenation. A Top: PECAM-1 (CD31; green) staining in seal and human endothelial cells. Middle: DiI-acetylated LDL (red) uptake by seal and human cells. Nuclei (blue) in the top and middle panels are stained with Hoechst 33342. Lower: Seal and human endothelial cells spontaneously form tubes when cultured in a 3D gel matrix. B Relative mRNA expression levels of the endothelial markers VE-cadherin (CD144) and PECAM-1 (CD31) in seal endothelial (purple) compared to placental trophoblast (red) cells, n = 3–5 replicates per group. Individual points are shown as white circles with gray borders. *p < 0.05. C Mitochondrial function at baseline and after hypoxia/reoxygenation in seal and human cells. Values are normalized to protein content per well. hxrx, hypoxia/reoxygenation. *p < 0.05 between species at baseline. †p < 0.05 between species after hypoxia/reoxygenation. Lettering indicates intraspecific changes between baseline and hypoxia/reoxygenation, n = 9 per group. D Extracellular acidification rate (ECAR) in seal and human endothelial cells at baseline and after hypoxia/reoxygenation, n = 9 per group. E, F Mitochondrial footprint (E) and mean mitochondrial network branch length (F) in seal and human endothelial cells after hypoxia/reoxygenation. Hypoxia exposure occurred for 1 or 6 h, followed by 30 min reoxygenation. Lettering indicates intraspecific changes between baseline and hypoxia/reoxygenation, n = 13–28 cells per group. G Representative images of human (top) and seal (bottom) endothelial cells stained with MitoTracker Red CMXRos after 0, 1, and 6 h hypoxia followed by 30 min reoxygenation. See Additional file 1: Fig. S1 for additional representative images. Scale bar in all images is 50 µm