Microcalorimetric studies on uraemic plasma

Area of Science:

• Biochemistry
• Thermodynamics
• Clinical Chemistry

Background:

• Uraemia is a complex clinical syndrome associated with kidney dysfunction.
• Altered metabolic processes in uraemia may affect plasma's thermodynamic properties.
• Heat production in biological systems is a key indicator of metabolic activity.

Purpose of the Study:

• To investigate and compare the heat production of human plasma in healthy and uraemic subjects.
• To explore the relationship between heat production, thiol group chemistry, and oxygen consumption in plasma.
• To identify potential correlations between plasma heat production and specific uraemic metabolites.

Main Methods:

• Direct isothermal microcalorimetry was employed to measure heat production.
• Plasma samples from both healthy and uraemic individuals were analyzed.
• Thiol group content and oxidation, as well as oxygen consumption, were assessed.

Main Results:

• Plasma from uraemic subjects exhibited significantly increased heat production compared to healthy subjects.
• In healthy plasma, heat production correlated with thiol group concentration and oxidation; this was not observed in uraemic plasma.
• Oxygen consumption in uraemic plasma was directly proportional to its heat production.
• A significant positive correlation was found between plasma heat production and creatinine concentration in uraemic patients.

Conclusions:

• Uraemia is associated with an elevated basal heat production in human plasma.
• The metabolic pathways contributing to heat production differ between healthy and uraemic plasma, with thiol group chemistry playing a role only in healthy individuals.
• Plasma heat production, particularly in relation to creatinine levels, may serve as a potential biomarker for assessing uraemic metabolic disturbances.