Muscular apoptosis but not oxidative stress increases with old age in a long-lived diver, the Weddell seal

The bottlenose dolphin (Tursiops truncatus): a novel model for studying healthy arterial aging

Endothelial function declines with aging and independently predicts future cardiovascular disease (CVD) events. Diving also impairs endothelial function in humans. Yet, dolphins, being long-lived mammals adapted to diving, undergo repetitive cycles of tissue hypoxia-reoxygenation and disturbed shear stress without manifesting any apparent detrimental effects, as CVD is essentially nonexistent in these animals. Thus, dolphins may be a unique model of healthy arterial aging and may provide insights into strategies for clinical medicine. Emerging evidence shows that the circulating milieu (bioactive factors in the blood) is at least partially responsible for transducing reductions in age-related endothelial function. To assess whether dolphins have preserved endothelial function with aging because of a protected circulating milieu, we tested if the serum (pool of the circulating milieu) of bottlenose dolphins (Tursiops truncatus) induces the same arterial aging phenotype as the serum of age-equivalent humans. We incubated conduit arteries from young and old mice with dolphin and human serum and measured endothelial function ex vivo via endothelium-dependent dilation to acetylcholine. Although young arteries incubated with serum from midlife/older adult human serum had lower endothelial function, those incubated with dolphin serum consistently maintained high endothelial function regardless of the age of the donor. Thus, studying the arterial health of dolphins could lead to potential novel therapeutic strategies to improve age-related endothelial dysfunction in humans.NEW & NOTEWORTHY We demonstrate that, unlike serum of midlife/older adult humans, age-matched dolphin serum elicits higher endothelial function ex vivo in young mouse carotid arteries, suggesting that the circulating milieu of bottlenose dolphins may be geroprotective. We propose that dolphins are a novel model to investigate potential novel therapeutic strategies to mitigate age-related endothelial dysfunction in humans.

Natural Tolerance to Ischemia and Hypoxemia in Diving Mammals: A Review

Reperfusion injury follows ischemia/reperfusion events occurring during myocardial infarction, stroke, embolism, and other peripheral vascular diseases. Decreased blood flow and reduced oxygen tension during ischemic episodes activate cellular pathways that upregulate pro-inflammatory signaling and promote oxidant generation. Reperfusion after ischemia recruits inflammatory cells to the vascular wall, further exacerbating oxidant production and ultimately resulting in cell death, tissue injury, and organ dysfunction. Diving mammals tolerate repetitive episodes of peripheral ischemia/reperfusion as part of the cardiovascular adjustments supporting long duration dives. These adjustments allow marine mammals to optimize the use of their body oxygen stores while diving but can result in selectively reduced perfusion to peripheral tissues. Remarkably, diving mammals show no apparent detrimental effects associated with these ischemia/reperfusion events. Here, we review the current knowledge regarding the strategies marine mammals use to suppress inflammation and cope with oxidant generation potentially derived from diving-induced ischemia/reperfusion.