The effect of the long-term administration of vasopressin on the development of the kidneys of growing lambs.

The effects of long-term administration of l-desamino-D-arginine vasopressin (dDAVP) on the macromorphology of the kidneys were studied in young growing lambs. Subcutaneous injections of dDAVP were started two weeks after birth and lasted for 13 weeks. Morphometric measurements showed that the volume of the cortex was reduced and both the height and volume of medulla were significantly increased in the dDAVP-treated lambs. The increase in the size of the medulla was mainly due to changes to the dimensions of the outer medulla. The surface area of the renal pelvis was enlarged by 29 per cent in the dDAVP-treated group. The mean (SEM) surface area of the renal pelvis of 15-week-old lambs was 5957 (365) mm2. These changes induced by an increased supply of vasopressin could have a beneficial effect on the recycling of urea and the concentrating ability of the kidneys.