NaHCO(3) does not affect arterial O(2) tension but attenuates desaturation of hemoglobin in maximally exercising Thoroughbreds.

This research paper examines the effects of administering Sodium Bicarbonate (NaHCO3) to racehorses before exercise. It particularly focuses on the impact on the horses’ arterial oxygenation during maximum effort exertion. Discoveries reveal that NaHCO3 does not improve oxygen retention in the horses’ arteries but lessens the desaturation of haemoglobin.

Research Background and Methodology

• The research was designed to understand what happens when metabolic alkalosis, induced by Sodium Bicarbonate (NaHCO3), is introduced to racehorses before they engage in maximum exercise.
• The experiments involved two sets of trials on 13 Thoroughbred horses. The horses were administered either intravenous physiological saline or NaHCO3 seven days apart.

Measurement and Examination of Variables

• Scientists examined blood-gas variables at rest and during incremental exercise. This escalated to 120 seconds of galloping at 14 m/s on a 3.5% uphill grade, which pushed horses to their maximum heart rate and induced pulmonary haemorrhage in all horses in both sets.
• The arterial oxygen (O2) tension and haemoglobin-oxygen saturation did not alter due to the administration of NaHCO3, although it did result in alkalosis (increase in alkalinity of the blood) and hemodilution (decrease in the concentration of cells and solids in the blood) in horses at rest.

Effects of Maximal Exercise

• When performing at maximum capacity, horses from both sets exhibited arterial hypoxemia (low blood oxygen levels), desaturation, hypercapnia (excessive carbon dioxide in the bloodstream), acidosis, an elevated body temperature (hyperthermia), and hemoconcentration (an increase in the concentration of cells and solids in the blood).
• Despite horses having higher arterial pH when treated with NaHCO3, there was a reduction in arterial oxygen content due to hemodilution.

Conclusion

• From the research findings, it is deduced that NaHCO3 administration before exercise does not affect arterial oxygen content or the severity of arterial hypoxemia in Thoroughbred horses performing high-intensity, short-term exercise.
• In contrast, there was a notable reduction in the desaturation of arterial haemoglobin in the horses treated with NaHCO3, signifying that it might play a role in oxygen transport during intense exercise.