Intraorgan pressure changes in rejecting kidney, liver, and heart transplants in the rat.

Intraorgan pressure was measured in DA kidneys, livers, and hearts after transplantation into Lewis rats. Recordings were obtained by passing a fine needle into the graft and measuring the resistance to the flow of saline. Rats with organ isografts (Lewis-to-Lewis) were used as controls, and a further control group comprised Lewis rats that had undergone left ureteric ligation. Following transplantation a rise in pressure was recorded from some of the isografts, it returned to base line levels by the second or third day. Similar changes were observed in the organ allografts, except that a second, much greater (P less than .05) rise soon followed. This was observed from day 3 onward in the case of the kidney and liver transplants, and from day 4 in the cardiac transplants. Control experiments showed that ligation of the ureter (as performed in all the kidney transplants) did not influence intrarenal pressure. It is concluded that a rise in intraorgan pressure is an early feature of rejection, and that pressure monitoring might be useful in patients with cardiac or liver transplants--in addition to those with kidney transplants in whom the test has been shown to be of value.