Meeting Abstract
Carbon monoxide (CO) is typically thought to be an exogenous gas that has toxic properties from binding tightly to the oxygen-carrying heme proteins (i.e. hemoglobin and myoglobin). However, the recent discovery of 1) heme degradation leading to endogenous carbon monoxide production, and 2) therapeutic properties from low concentrations of CO has shed new light on the gas. The most promising therapeutic potential has been attributed to CO reducing injuries associated with ischemia-reperfusion events (e.g. inflammation, apoptosis and cell proliferation). Due to the increased heme protein stores (hemoglobin and myoglobin) and ischemia-reperfusion events associated with the dive response in diving animals, we investigated endogenous CO levels in the breath (ppm CO) and blood (% carboxyhemoglobin – COHb) of four species of cetaceans (Bottlenose dolphins, short-finned pilot whales, killer whales and beluga whales) and two pinniped species (northern elephant seals and Hawaiian monk seals). Our findings show that animals with the most elevated heme protein stores (elephant seals, monk seals and beluga whales) have exhaled CO levels (23ppm, 6ppm and 7ppm, respectively) that mimic those seen in human cigarette smokers (> 6 ppm). However, only the elephant seal displayed elevations in blood CO with values as high as 17.6% COHb (5.8X values seen in chronic cigarette smokers). The high values seen in the elephant seals are likely due to elevated erythrocyte turnover in a species with the highest mass specific mammalian blood volume and hemoglobin concentrations. We suggest that these natural elevations in CO potentially serve to protect the animals against injuries related to consistent ischemia-reperfusion events associated with a lifestyle of breath-holding and the dive-response.
