Role of a renal arginylesteropeptidase in the production of a renotrophic factor in unilaterally nephrectomized rats

Kidney function after unilateral nephrectomy

Immediately after unilateral nephrectomy ( uNX ) some different mechanisms of compensatory adaptation begin to act followed by a restoration of sufficient kidney function in a short time period. Beside biochemical changes early compensatory hypertrophy of the remaining kidney occurs. Simultaneously, functional adaptations of renal blood flow, glomerular filtration and exertion of electrolyte and xenobiotics take place. With a suitable pretreatment it is principally possible to accelerate the regeneration phase. Thus the phase of reduced excretion capacity of tubularly secreted xenobiotics after removal of one kidney can be shortened or prevented.

Humoral factors in regulation of compensatory renal hypertrophy

Compensatory renal hypertrophy in transplanted kidneys shows that the major regulators are humoral. Crosscirculation experiments are confirmatory indicating further that the regulators are short-lived and must be consistently present during the early phases of hypertrophy. Controls are difficult to achieve in other systems; variables relate to nutrition, means of assay, pharmacokinetics, and abnormalities produced by the experimental model itself. A simple hypothesis to account for the events precipitating renal hypertrophy might integrate the onsets of renal hyperemia soon after contralateral nephrectomy with the activation of pre-existing stimulators specific for the kidney.

The control of liver regeneration after partial hepatectomy in the rat

1. Normal rat liver slices were incubated for 24 h in culture medium to which had been added freeze-dried plasma, prepared from the blood of rats which had undergone partial hepatectomy (60-70% of liver removed) 10 min, 4 or 24 h previously. No changes in the dry weight of the slices were observed. 2. Similarly, there were no changes in the dry weight or protein content of incubated liver slices when freeze-dried plasma prepared from the blood of rats unilaterally nephrectomized 10 min, 4 or 24 h previously was added to the culture medium. 3. Slices from the remaining liver stump, taken 4 h after partial hepatectomy (60-70% of liver removed) and incubated for 4 h in culture medium, did not release a factor capable of increasing the dry weight of normal liver slices incubated in the same medium. 4. After partial hepatectomy (60-70% of liver removed), there was no increase of guanosine 3':5'-cyclic monophosphate in the remaining part of the liver. 5. No measurable amount of esterase activity was found in normal liver or in the remaining liver stump after partial hepatectomy (60-70% of liver removed). 6. It is suggested that the stimulatory mechanism for liver regeneration is of a different nature from that involved in compensatory renal hypertrophy.