The wound contraction model described in Part I was used to study topically applied, recombinant platelet-derived growth factor (rPDGF-BB) and wound contraction in normal and steroid-impaired rats. Circular wounds 4 cm in size were made on the dorsum of the rats with halothane anesthesia. Five groups of 20 normal rats each were treated with the vehicle alone and four concentrations of rPDGF-BB (0.5, 1.0, 3.0, and 10.0 µg/ml). Four groups of 20 steroid-impaired rats each were treated with the vehicle alone and three concentrations of rPDGF-BB (0.5, 1.0, and 3.0-µg/ml). The wounds were dressed with 2x2 gauze, Adaptic, 4x4 gauze, and Tubigrip. The investigators were blinded to the treatments until the completion of the experiment, and the treatments were applied in random order. Dressings were changed every 2 to 3 days for 14 days and the wound areas were determined, expressed as a fraction of the original, and plotted versus time. The areas under the curves and the means of the fraction open each day were compared between groups using Student's t-test.The treatment with 3.0-µg/ml rPDGF-BB accelerated the rate of wound contraction in the steroid-impaired animals (p<0.05).