In non-amniotes, like fish, the arteries supplying oxygen to the heart originate directly from the gills.

 In non-amniotes, like fish, the arteries supplying oxygen to the heart originate directly from the gills.

 In amniotes, such as mice, these vessels, known as aortic subepicardial vessels (ASVs), undergo reorganization during development to form novel coronary arteries that branch near the heart. This evolutionary change is likely linked to the loss of gills during the transition to a terrestrial lifestyle. Credit: 2023, H. Higashiyama

The researchers speculated that this was necessary to enable a thickening of the human heart's ventricle wall, so that it could handle high physiological activity, such as the elevated blood pressure that maintains amniotes' high metabolic capacity (the ability to take on oxygen and circulate it in the blood).

"This research broadens the range of animal models available for studying heart diseases and their treatments," said Higashiyama. "Next we would like to gain a deeper understanding of the molecular processes involved in coronary artery remodeling. By doing so, we can uncover the mechanisms of 'how' the mammalian- and reptilian-type coronary arteries evolved and potentially shed light on human congenital heart abnormalities and diseases."