6 Kidney-Explantation and Hypertension 



cither because the response is somehow different or because of compensation 

 and adjustment by an overwhelmingly powerful nervous control. If a delayed 

 hypertension follows extremely long ligations of explanted kidneys, such as six 

 or seven hours, there is evidence that this is merely a nervous or psychic phe- 

 nomenon due to the pain of local inflammation. Attempted general theories of 

 hypertension must therefore take account of the complexity of blood pressure 

 regulation. 



The proof of the specificity of the hypertensive substance obtained from 

 kidney extracts or from the asphyxiated living kidney is that it is not obtain- 

 able from any other organ. One of the proofs of the nervous character of the 

 above-described form of acute hypertension is that it is nonspecific. The re- 

 sults of kidney ligation are fully duplicated by ligations of the testes, legs, tail 

 and other parts. A tourniquet on the tail offers the most convenient routine 

 method, because of absence of the paralysis which results in the legs. With any 

 of these methods there is the same acute hypertension as with the kidneys and 

 also the same rapid fall after removal of the tourniquet. Particularly with 

 ligations of the scrotum for three to four hours and of the tail for seven or 

 eight hours it is possible to demonstrate a secondary hypertension following 

 removal of the tourniquet, due to inflammatory pain, especially in nervous 

 dogs. With this exception, a hypertension following restoration of circulation 

 is as completely lacking with these various organs as it is with the kidney. 



When the ligations are repeated, whether at intervals of one or many days, 

 the same acute hypertension continues to occur and there is no loss of response 

 with either the kidneys or the tail. But no chronic hypertension results in the 

 case of the tail, as far as observable with frequently repeated ligations for six 

 months. Also, no chronic hypertension has yet been obtained with ligations 

 limited to one kidney, leaving the other intact. Chronic hypertension is ob- 

 tainable, as described years ago by Loesch, by repeated clamping of the pedi- 

 cles of both kidneys, or of one kidney when the other has been removed. The 

 reasons why the original Loesch method is more effective than clamping or 

 ligation outside the skin, also why some dogs develop uremic tendencies while 

 the majority retain good kidney function, and various other questions remain 

 at present undecided because of the long suppression of the work. 



3. Pathology of the Kidneys 



Loesch was not only the first to produce true chronic renal hypertension in 

 dogs by means of the above-described method of intermittent clamping, but 

 also as a pathologist he gave special attention to the accompanying anatomic 

 changes in the kidneys. Figures 1, 2, and 3 are reproduced from microphoto- 

 graphs prepared by Loesch, and his papers sufficiently pointed out the simi- 

 larity of such lesions with the infiltrating and sclerosing processes found in 

 some human cases with hypertension. 



In the recently resumed research the pathological examination has been 

 undertaken by Dr. W. E. Youland. In view of the intervening developments 



