Intensity-dependent effects of acute submaximal exercise on the pharmacokinetics of bromsulphalein in horses.

This research studied the effects of acute submaximal exercise on how quickly a compound called bromsulphalein (BSP) is cleared from horses’ bodies. It found that exercise intensity can limit blood flow to the liver, slowing the clearance of BSP and potentially other drugs from the horse’s system.

Methodology

• The study involved eight adult Standardbred mares.
• The horses were exposed to four different exercise intensities: at rest, and at 40%, 60%, and 80% of their maximal oxygen consumption.
• After running on a treadmill at the required speed for one minute, the horses were given an intravenous injection of BSP (5 mg/kg of body weight).
• The horses continued running at the set speed for an additional 15 minutes.
• Blood samples were taken every two minutes for half an hour, and the plasma concentration of BSP was measured using spectrophotometry.

Results and Analysis

• It was found that the clearance of BSP from the horses’ blood and plasma decreased significantly with exercise and was directly related to exercise intensity.
• No exercise-induced differences were found in the volume of distribution of BSP.
• The time it took for half of the BSP to be eliminated from the body increased significantly with higher exercise intensity, also showing a linear relationship.

Conclusion

• The results show that acute submaximal exercise has a significant effect on how quickly BSP is cleared from a horse’s body.
• This could be due to exercise-induced decreases in splanchnic blood flow limiting the amount of blood the liver receives, reducing its capability to clear BSP.
• This could lead to prolonged plasma concentrations of BSP, and potentially other drugs that are effectively extracted by the liver, in horses exercising at submaximal intensities.