Eleanor Kellon, VMD
I just uploaded a file https://ecir.groups.io/g/main/files/Endothelin-1 that studies how exposure to elevated insulin levels increases the resistance to blood flow in the hoof and this is tied to endothelin-1. In normal circumstances, insulin counteracts endothelin-1 by stimulating nitric oxide release, which dilates the vessels. When constantly exposed to high levels of insulin, the cells become resistant to its effects. This explains both endocrinopathic laminitis and also why many of these horses are more cold sensitive than normal horses. Cold only adds to the pre-existing vessel constriction.
If you are not up to reading all the scientific details, just read the abstract, introduction and discussion at the end.
Eleanor in PA