In vitro responses of insulin resistant and nonresistant digital vessels of healthy and laminitic horses (851.11)

Abstract

Hyperinsulinemia leads to insulin resistance of blood vessels and interferes with circulation of lamina of the equine foot. The objective of the study was to compare the digital vessel responses of clinically healthy and laminitic horses with and without experimental induction of insulin resistance. Vessel segments (artery and vein) collected after euthanasia, were cut into 3 mm wide rings and were prepared in tissue baths containing Tyrode’s solution for response studies. Two rings from each horse were used as non‐resistant and two were made insulin‐resistant. All rings were contracted with phenylephrine (10‐6.5M). When the contraction reached a plateau, insulin (10‐5M) was added and the response monitored. The response to insulin was calculated as a percentage of the phenylephrine response. The results showed that the responses of the non‐resistant rings differed significantly between the groups. However, when all rings were made insulin‐resistant, the significance between the groups disappeared. In the laminitic group, responses of resistant and non‐resistant rings did not differ, whereas in the healthy group, the vessel responses differed significantly. In all experiments, arterial and venous rings followed the same pattern but the magnitudes were greater in arterial rings. The findings suggest that the vessel responses to insulin are altered in laminitis which could be due to insulin resistance.Grant Funding Source: Supported by Equine Health Studies Program of LSU‐SVM