Sheep lactate entry-rate measurements: error due to sampling jugular blood

Area of Science:

• Biochemistry
• Physiology
• Animal Science

Background:

• The continuous infusion isotope-dilution method is crucial for quantifying metabolic rates.
• Accurate blood sampling is essential for reliable calculations in metabolic studies.

Purpose of the Study:

• To evaluate the accuracy of jugular venous sampling for estimating lactate formation rates using isotope dilution.
• To investigate potential discrepancies between arterial and jugular venous measurements.

Main Methods:

• Simultaneous carotid arterial and jugular venous blood sampling in four sheep.
• Primed continuous infusion of L-[U-14C]lactate.
• Analysis of lactate concentration and specific radioactivity in blood samples.

Main Results:

• Jugular sampling significantly overestimated total net lactate formation (0.394 mg C/min/kg) compared to arterial sampling (0.302 mg C/min/kg).
• A negative arteriovenous difference for lactate across head tissues contributed to the overestimation.
• The findings indicate a systematic error associated with jugular sampling in this model.

Conclusions:

• Jugular venous sampling may not be suitable for accurate estimation of lactate formation rates in sheep using this method.
• Arteriovenous differences must be considered when interpreting results from venous sampling in isotope-dilution studies.
• Further validation of sampling techniques is recommended for metabolic research.