Cold-induced perturbation of cutaneous blood flow in the rat tail: a model of nonfreezing cold injury.

Cold-induced alteration of cutaneous blood flow, measured with laser-Doppler flowmetry, was studied in a rat tail model of nonfreezing cold injury (NFCI). The NFCI-inducing condition consisted of prolonged tail immersion in 1 degree water. Before exposure to the injury condition, tail blood flow (laser Doppler flux) during brief 3 degrees immersion showed cold-induced cycles of vasoconstriction followed by cold-induced vasodilation (CIVD). Tail temperature exhibited cyclic patterns similar to blood flow in response to cold water immersion. Cold exposures to 1 degree for 1 or 3 hr induced no systematic change; however, cold exposures of 6 or 9 hr induced profound and long-lasting blood flow and temperature deviations. Following the cold injury condition, CIVD was completely absent and remained absent for several weeks, suggesting that CIVD loss is an important component in development of NFCI. Cold-induced disturbances of cutaneous blood flow in the rat tail consisted of a sequence of distinctive stages analogous to those described in human NFCI. These stages were evidenced initially by several days of reduced blood flow and thermal sensitivity, followed in a week by a hyperemia stage, and later by enhanced vascular and thermal sensitivity. The cutaneous blood flow alterations and sequence of variations following prolonged cold exposure suggest that the rat tail may be a valid model of human NFCI.