169 



THE EFFECT ON RENAL EFFICIENCY OF LOWERING 



THE BtOOD-PRESSURE IN CASES OF HIGH 



BLOOD-PRESSURE^ 



By CHARLES REID 



(From the Physiological Laboratory, University of Aberdeen) 



The following investigation was undertaken to ascertain the effects, especially 

 as regards the efficiency of the kidneys, of lowering the hypertension present in 

 cases which did and others that did not show evidence of renal disease. The plan 

 adopted was to make the following examinations on each case before, during, and 

 after periods of administration of vasodilator drugs ; the amounts of urea and 

 non-protein nitrogen in the blood, the power of the kidney to concentrate urea 

 after a dose of 15 grm. urea (MacLean's test (9)), the total amount of urea and the 

 total volume of urine excreted, records of blood-pressure, pulse, respiration, and 

 general condition of the subject being made also. 



A current conception of elevated blood-pressure is that, while attended 

 by drawbacks in the way of increased heart work and stress on the ai-terial walls, 

 it is in large measure a compensatory process in the organism. This view has 

 gained wide acceptance, and many observers have emphasized the inadvisability of 

 indiscriminate lowering of the pressure by such artificial means as the use of vaso- 

 dilating drugs. Cases have been cited of deterioration in general condition being 

 associated with lowering of high pressures, and, on the other hand, improvement 

 in health being attended, not by lowering, but by some further rise of an already 

 elevated pressure. The high-pressure levels in such cases are regarded as not being 

 excessive in the circumstances, but rather as optimal, or at least not markedly 

 superoptimal under the conditions present in the body at the time. When 

 no symptoms are in evidence artificial reduction of the pressure is held to 

 be inadmissible. Even when symptoms are present it is conceivable that a 

 necessary compensatory action may be exercised in some respects, though the 

 high pressure may involve disturbances in other respects. 



In view of the separation of a new antipressor piinciple from hepatic 

 extracts in comparative purity by James, Laughton, and Macallum (7), and 

 of the prospect of this method of lowering the raised blood-pressure being given 



' Received December 10, 1925. 

 Q.J.M.,July, I9a6.] F f 



