Effects of the rate of insulin infusion during isoglycemic, hyperinsulinemic clamp procedures on measures of insulin action in healthy, mature thoroughbred mares.

This study investigates whether the rate of insulin infusion during certain medical procedures impacts insulin responses in healthy, mature horses. The results indicate that different rates of insulin infusion do alter certain measures of insulin action, therefore they highlight the need to standardize insulin infusion rates during these procedures to ensure comparability of results between different studies.

Objective of the Study

• The study aimed to understand if the rate at which insulin was administered in isoglycemic hyperinsulinemic clamp procedures could influence the readings of insulin action in mature, healthy horses.

Methodology

• The research involved eight thoroughbred mares undergoing hyperinsulinemic clamp procedures of 2-hours duration.
• Insulin was infused at four different rates labeled as CON (0), LOWINS (1.2), MEDINS (3), and HIGHINS (6) mU · kg(-1) · min(-1).
• The amount of a dextrose solution was altered during the procedures to maintain a constant blood glucose level within 10% of the base reading.
• Measurements taken included plasma insulin concentrations and glucose infusion rate. This helped compute the insulin concentration-to-rate of glucose infusion ratio, an indicator of insulin’s effect on glucose disposal.

Results

• The rate of glucose infusion rose with an increase in the insulin infusion rate.
• The LOWINS treatment showed the highest plasma insulin concentration-to-rate of glucose infusion ratio, which dropped by 62% and 84% for the MEDINS and HIGHINS treatments, respectively.
• Regardless of different insulin infusion rates, by the 30-minute mark, plasma non-esterified fatty acid concentrations saw a drop from the base reading in the LOWINS, MEDINS, and HIGHINS treatments.
• Rates of insulin infusion did not show any effect on jugular vein plasma nitric oxide and endothelin-1 concentrations.

Conclusion

• The outcomes of the study revealed that different rates of insulin infusion during these procedures can indeed affect certain measures of insulin action.
• This highlights the importance of standardizing insulin infusion rates during hyperinsulinemic clamp procedures to make data collected across different studies comparatively viable and reliable.