Methods Experimental model. Albino rabbits weighing 2.0 to 2.5 kg were used. Unilateral progressive Masugi nephritis was produced according to the method of Sarre and Wirtz [7] and modified by Nagasawa [8], which has been described in a previous report [9]. Briefly, after ligation of the right renal artery with fine silk, duck anti-rabbit kidney serum (nephrotoxic serum or NTS) was injected into the ear vein (2.5 ml! kg of body wt). Twenty minutes later, the ligature was released. In this experimental model, the non-ligated kidney is known to progress to a contracted kidney over a period of three or more months. We were able to confirm this phenomenon (Fig. 1). Experimental groups: Group 1 (simultaneous NTS+ H—one week group). Simultaneously with the