Lovering, AndrewDiMarco, Kaitlyn2024-03-252024-03-252024-03-25https://hdl.handle.net/1794/29280Individual variability in the cardiopulmonary system is often ignored in favor of focusing on group or treatment means. Erythropoietin (EPO) concentrations in response to renal hypoxemia, sea level hemoglobin (Hb) mass (Hb mass), and pulmonary vascular pressure changes in response to environmental stimuli are known to be markedly varied among individuals, yet very little research examines factors that may be responsible for that variability. Iron availability, immune system activity, and the presence or absence of a patent foramen ovale (PFO) are all factors that may play a modulatory role in EPO regulation, Hb mass, and pulmonary vascular tone regulation, yet our understanding of these factors in humans is largely unknown. In Chapter IV, we demonstrate that carbon monoxide (CO) inhalation (COi) and hot water immersion (HWI) independently and in combination (COi + HWI) increased EPO concentration to the same degree. Importantly, the increase in EPO was driven by females. Baseline iron availability and inflammatory cytokine concentrations did not predict EPO concentration in response to COi or HWI. This study emphasizes the need for future studies to examine mechanisms underlying sex differences in EPO concentrations in response to COi and HWI. In Chapter V, we show that some inflammatory cytokine concentrations and white blood cell counts moderately predicted Hb mass, but iron availability was the strongest predictor of Hb mass. The presence of a PFO did not alter Hb mass, although we do report lower ferritin in males with a PFO compared to males without a PFO. This study provides novel information that will provide direction to future research looking to utilize interventions aimed to alter Hb mass. Lastly, in Chapter VI, we demonstrated that SCUBA dives not requiring decompression on the ascent do not increase pulmonary pressure or resistance. However, some cytokine concentrations increased post SCUBA diving, so future research should examine the role of inflammatory cytokines in modulating pulmonary pressure during SCUBA dives requiring decompression that elicit increases in pulmonary pressure and resistance. This dissertation includes previously unpublished co-authored material.en-USAll Rights Reserved.ErythropoietinInflammationIron statusPulmonary vascular toneRed blood cellSCUBA diving physiologyElectronic Thesis or Dissertation