Blood ammonia concentration in mice: normal reference values and changes during growth.

Area of Science:

• Physiology
• Biochemistry
• Animal Models

Background:

• Accurate blood ammonia concentration reference values are essential for toxicological and physiological studies in mice.
• Factors influencing ammonia determination require thorough investigation to ensure reliable data.

Purpose of the Study:

• To establish normal reference values for blood ammonia concentration in mice.
• To investigate the impact of age, sex, strain, and blood sampling site on ammonia levels.

Main Methods:

• Microdiffusion method was employed for blood ammonia determination.
• Blood samples were collected from various sites including tail, left ventricle, orbital sinus, and right auricle.
• Ammonia levels were analyzed across different age groups, sexes, and mouse strains.

Main Results:

• Blood ammonia levels were significantly higher in samples from the tail and left ventricle compared to the orbital sinus and right auricle.
• No significant differences in blood ammonia concentration were observed between sexes or strains.
• Neonatal mice showed elevated ammonia levels, peaking 24 hours after birth and stabilizing by 15 days.
• Post-weaning mice exhibited a wide range of ammonia concentrations (38-123 µg/dL), with a mean of 79 ± 18 µg/dL, irrespective of age, sex, or strain.

Conclusions:

• Blood sampling site significantly influences ammonia measurements in mice.
• Age-dependent variations in blood ammonia are prominent in neonatal mice but normalize post-weaning.
• Established reference ranges for post-weaning mice are valuable for future research, considering sampling site and age factors.