Age and Renal Disease 257 



among the measures that Selye uses, as he says, to "sensitize" 

 the rat to the damaging effect of hormones. Nevertheless, 

 we have found that no overgrowth of the kidney occurs in 

 hypophysectomized rats with hypothalamic lesions, although 

 they still have increased appetites, and other tissues, such as 

 the liver and gastrointestinal tract, hyperti'ophy "(Kennedy 

 and Parrott, 1958). We also confirmed, as White, Heinbecker 

 and RolfP (1941) first showed, that compensatory growth after 

 partial nephrectomy required the presence of the pituitary. 

 However, the late renal changes in our rats were associated 

 with a catabolic rather than an anal^olic state of the body as a 

 whole, so it seems unlikely that growth hormone was being 

 secreted in excess. 



There remains the possibility that adrenal overactivity 

 plays a part in the final renal breakdown. Adrenal enlarge- 

 ment and the nephrotic character of the renal defect (Saxton 

 and Kimball, 1941) have been mentioned. A number of 

 workers have shown that complete or extensive partial 

 nephrectomy is followed by increased urea production 

 (Bondy and Engel, 1947; Persike and Addis, 1949; Persike, 

 1950; McCance and Morrison, 1956). This has recently been 

 shown to be due to increased protein catabolism in the liver 

 (Sellers, Katz and Marmorston, 1957), so it may well be a 

 result of increased adrenal activity. Overdosage with adrenal 

 steroids can certainly cause renal breakdown associated with 

 extensive tubular hyperplasia, although the immediate cause 

 may be potassium deficiency (Follis, 1948) or sodium reten- 

 tion (Ingle, 1958) associated with such experiments. We have 

 learned little from the serum electrolytes of our rats, because 

 any changes that might implicate the adrenal are obscured 

 by the general electrolyte retention of incipient uraemia. 

 Morrison and Gordon (1957), however, have shown that 

 increased urea excretion during starvation occurs both in 

 partially nephrectomized and senile rats before obvious renal 

 damage and is accompanied by an increased potassium loss. 



Another renoprival effect that may hasten the end of the 

 kidney is hypertension, although again the exact relation 



AGEING— IV— 9 



