The Improvement Of Microcirculation In Rabbit Acute Wound By V.A.C And Its Relation With NO, ET-1 And NOS

Wound healing is a complicated and ordered biological course, which includes hemostasis of wound, inflammatory reaction, proliferation, differentiation, epithelization and migration of cell,and synthesis, maturation and remodeling of matrix. The nutrition of skin is mainly provided by microcirculation. During the course of wound healing, the tissue needs sufficient nutrition and the energy metabolism is strengthened. So the favorable microcirculation function is vital for the normal wound healing.As a new therapeutic method in recent years, Vacuum-assisted closure (V.A.C.) has been applied effectively in the treatment of the wound. But we still know little about its mechanism. Our department has made serial research on the mechanism of V.A.C. It has been proved that V.A.C. can effectively improve the microcirculation of wound and increase the blood supply of microcirculation, which accelerates the wound healing. This experiment aims to make further study on the mechanism of its improvement of microcirculation and the promotion of wound healing by V.A.C. We studied as follows in two parts.1. A rabbit ear acute full-thickness skin loss model was established.Twenty rabbits were randomly divided into the treatment group treated with V.A.C. and the control group treated with normal dressing.The content of endothelin(ET-l) and nitric oxide(NO) were measured at different times before and after the formation of the wound by drawing blood.Meanwhile, the blood flow of the microcirculation of the wound was measured with laser doppler fiowmeter. And the time of the wound healing were also observed. Results: Because of the operative stimulus after the formation of the wound, the content of the ET-1 in blood plasma increased sharply, which led to the intense contraction of microvascular. And the blood flow of the microcirculation in the wound decreased to 20% the preoperative level at 1 hour . The level of NO increased slowly and decreased gradually. The blood flow of the microcirculation in the wound increased to 80% preoperative level at day 7. Treated with V.A.C, the content of the ET-1 decreased rapidly to the preoperative level. The content of NO was significantly higher than that in the control group and still maintained high level at day 7. The blood flow of the microcirculation in the wound increased to about double preoperative level until the wound healed. The healing time: the treatment group treated with V.A.C. was (9.00±0.53) days, and the control group was (12.00±0.32) days. 2. An acute back skin wound model of rabbit was used to examine the influence of V.A.C. on the contents of eNOS, iNOS in the tissues of the wound. At different points of healing time, the contents of eNOS, iNOS in tissues of the wound were examined by immunohistochemistry. Results: During the process of wound healing, the expression of iNOS increased generally in both groups, but compared with the control group, it decreased more rapidly during the later period of wound healing in the treatment group. The level of eNOS of the treatment group was significantly higher than that of the control. It peaked at day 3 and maintained high level during the healing process.