Mapping of ATP, glucose, glycogen, and lactate concentrations within the arterial wall

Objective - In large- and medium-sized arteries, the diffusion distances for oxygen and nutrients are long. This has been suggested to make these vessels prone to develop local energy metabolic deficiencies that could contribute to atherogenesis. To validate this hypothesis, we introduced a new method to measure energy metabolites within the arterial wall at high spatial resolution. Methods and Results - Bioluminescence imaging was used to quantify local metabolite concentrations in cryosections of snap frozen (in vivo) and incubated pig carotid artery rings. Incubation at hypoxia resulted in increased lactate concentrations, whereas ATP, glucose, and glycogen concentrations were decreased, especially in the mid media, where concentrations of these metabolites were close to zero. In snap frozen arteries, glycogen concentrations were markedly higher in deep layers of the media than toward the lumen. ATP, glucose, and lactate were more homogenously distributed. Conclusions - Bioluminescence imaging is a new and powerful tool to assess arterial wall energy metabolism at high spatial resolution. Our experiments demonstrate heterogeneous distributions of energy metabolites under hypoxic in vitro conditions. Furthermore, we show that glycogen concentrations are higher in deep medial layers in vivo. This might represent a local adaptation to a low-oxygen microenvironment.