Effects of haemorrhage on wound strength and fibroblast function

The impairment of healing in laparotomy wounds in rats with compensated oligaemia has been studied in two parallel investigations. Animals bled 1 ml/100 g body weight (bled) were compared with unbled animals undergoing the same operation (control). Firstly, wounds were assessed after 22 days for strength of skin and muscle layers (11 control: 9 bled). Both layers were significantly weaker in bled animals; by 36 per cent for skin (P less than 0.02) and by 22 per cent for muscle (P = 0.02). Secondly, wound fibroblast function was assessed after 10 days by quantitative histology and autoradiography (30 control: 31 bled). There were no significant differences between the two groups for fibroblast density, replication ([3H]thymidine), or general protein synthesis ([3H]leucine). Bled animals had less dense collagen packing by 21 per cent (P less than 0.01), but 33 per cent more incorporation of ([3H]proline) by fibroblasts (P less than 0.01) compared with control animals. The effect of compensated oligaemia on wound healing is more marked in skin than in muscle; it appears to be a specific increase in collagen turnover with the increase in reabsorption exceeding that in synthesis.