Meeting Abstract
Small mammals tend to have shorter lifespans and lower whole animal metabolic rates, whereas large mammals typically have longer lifespans and higher whole animal metabolic rates. However, domestic dogs, Canis lupus familiaris , are an anomaly: small breed dogs have lower whole animal metabolic rates, yet they have longer lifespans compared with large breed dogs that have higher whole animal metabolic rates, but shorter lifespans. In this study, we looked at cellular metabolic rates as small breed and large breed dogs age. Primary dermal fibroblasts were isolated and grown in tissue culture from skin samples that were obtained from veterinarians. We measured basal oxygen consumption, proton leak, maximal oxygen consumption, non-mitochondrial oxygen consumption and rates of glycolysis using a Seahorse XF96 oxygen flux analyzer. Our results show basal oxygen consumption, proton leak, maximal oxygen consumption and non-mitochondrial respiration in small breed dogs had increased rates as they aged, whereas, we see the opposite pattern in large breed dogs showing a decrease in rates of all parameters of cellular oxygen consumption as they age. We see that as both size classes age, rates of glycolysis tend to increase. This implies that in large breed dogs there is a reduction in oxygen consumption pathways with age, indicating that they are relying less on oxidative phosphorylation as the main source of ATP production in cellular respiration, a trend that may suggest that older dogs cannot produce ATP at the same efficiency as they did at a younger age. Additionally, increases in cellular oxygen consumption in large breed puppies may increase RS (reactive species) production, thus, increasing the amount of cellular damage that happens early on in large breed dogs, potentially explaining their shorter lifespans.
