Carbonic anhydrase activity in the red blood cells of sea level and high altitude natives

TMT-Based Plasma Proteomics Reveals Dyslipidemia Among Lowlanders During Prolonged Stay at High Altitudes

Acute exposure to high altitude perturbs physiological parameters and induces an array of molecular changes in healthy lowlanders. However, activation of compensatory mechanisms and biological processes facilitates high altitude acclimatization. A large number of lowlanders stay at high altitude regions from weeks to months for work and professional commitments, and thus are vulnerable to altitude-associated disorders. Despite this, there is a scarcity of information for molecular changes associated with long-term stay at high altitudes. In the present study, we evaluated oxygen saturation (SpO₂), heart rate (HR), and systolic and diastolic blood pressure (SBP and DBP) of lowlanders after short- (7 days, HA-D7) and long-term (3 months, HA-D150) stay at high altitudes, and used TMT-based proteomics studies to decipher plasma proteome alterations. We observed improvements in SpO₂ levels after prolonged stay, while HR, SBP, and DBP remained elevated as compared with short-term stay. Plasma proteomics studies revealed higher levels of apolipoproteins APOB, APOCI, APOCIII, APOE, and APOL, and carbonic anhydrases (CA1 and CA2) during hypoxia exposure. Biological network analysis also identified profound alterations in lipoprotein-associated pathways like plasma lipoprotein assembly, VLDL clearance, chylomicron assembly, chylomicron remodeling, plasma lipoprotein clearance, and chylomicron clearance. In corroboration, lipid profiling revealed higher levels of total cholesterol (TC), triglycerides (TGs), low-density lipoprotein (LDL) for HA-D150 whereas high density lipoproteins (HDL) levels were lower as compared with HA-D7 and sea-level indicating dyslipidemia. We also observed higher levels of proinflammatory cytokines IL-6, TNFα, and CRP for HA-D150 along with oxidized LDL (oxLDL), suggesting vascular inflammation and proartherogenic propensity. These results demonstrate that long-term stay at high altitudes exacerbates dyslipidemia and associated disorders.

Does altitude affect blood gases in hemodialysis patients?

INTRODUCTION

This study aimed to determine whether predialysis blood gases is affected by altitude differences in hemodialysis patients with arteriovenous fistulas living in Turkey at three different altitudes.

METHODS

Patients' predialysis blood gases were compared by standardizing both arterial blood gases collections and working methods for patients undergoing hemodialysis using a dialysate with the same properties at altitudes of 30 m (sea level), 1020 m (moderate altitude), and 1951 m (high altitude).

FINDINGS

Blood gases disorders were detected in 32 (82.1%) high altitude group patients, whereas 49 (74.2%) sea level group patients had no blood gases disorders (P < 0.001). pH values in the high altitude group were significantly lower than those in the other groups, and the pH increased as altitude decreased (P < 0.001). The partial pressure of carbon dioxide (PaCO₂ ) values was higher in the sea level group than in the other groups and increased at lower sea levels (P < 0.001). Bicarbonate values were significantly higher in the sea level group than in the other groups and increased at lower sea levels, similar to PaCO₂ values (P < 0.001). The partial pressure of oxygen (PaO₂ ) values in the high altitude and sea level groups were significantly higher and increased at lower sea levels (P < 0.001). The oxygen saturation (SaO₂ ) values were significantly lower in the high altitude group than in the other groups and increased gradually at lower sea levels (P < 0.001).

DISCUSSION

Predialysis metabolic acidosis was more pronounced in patients undergoing hemodialysis at high altitudes, whereas PaCO₂ , PaO₂ , and SaO₂ values were lower.