176 • QUARTERLY JOURNAL OF MEDICINE 



With regard to the general effects of lowering blood-presaure, it was excep- 

 tional to get any evidence of disturbance in the condition of the patient, except 

 in the cases where the vasodilator drug was used in the larger doses over a longer 

 period. Occasionally slight palpitation and headache were complained of in 

 one or two cases. There was no complaint of giddiness or faintness, and no 

 noticeable change in the colour of the face was observed. The chief complaints 

 in the cases exhibiting intolerance to the drug were of pain and throbbing in the 

 head. Pulse and respiration generally were but little affected (as shown by the 

 recorded figures in Table I), being, as a rule, increased very slightly in frequency. 

 Oedema, which was present in two or three cases, was not increased by the use of 

 the vasodilator drug. One case (acute nephritis), which showed a slight amount 

 of oedema, exhibited a marked increase in the amount of urine and urea 

 excreted, and a fall in the blood urea and blood-pressure during the time that the 

 drug was being used ; there was disappearance of the oedema. Another case of 

 acute nephritis with a very large amount of oedema was not affected adversely. 

 The amount of urine increased to some extent, although the drug was employed 

 for a period extending over a week. This is suggestive with regard to the 

 question of salt retention, since the latter is readily indicated by evidences 

 of oedema. 



Although the effects of a single dose of liquor trinitrini on the systemic* 

 blood-pressure are diminished in a hour or so and pass off according to different 

 observers in periods varying up to two and a half hours, the decrease in the 

 amount of urine secreted throughout the three hours after the administration of 

 15 grm. urea in cases which had been previously under the iufluence of repeated 

 doses of nitrite, compared with the amount obtained on days on which the test 

 was carried out without the administration of nitrite, suggests that the effects of 

 repeated doses of nitrites on the kidney outlast those of a single dose on 

 the systemic blood-pressure. Erythrol tetranitrate, used in a number of cases, 

 has a more prolonged action. As a result of the above-mentioned decrease in the 

 amount of urine leading to an artificial increase in the specific gravity and urea 

 percentage of the urine, vasodilator drugs should not be given during the applica- 

 tion of MacLean's test, although cases giving urea percentages much under 2 

 are unlikely to show specimens of urine above this percentage even during 

 the administration of the vasodilator drug. In connexion with this an interesting 

 point comes up. For example, in the application of MacLean's test to Cases 1, 7, 

 10, 17, 21, under normal conditions, the second hourly specimen of urine gives 

 urea percentages of 17, 1*2, 1-5, 0-9, 2-1, respectively. During the period of 

 lowered pressure the corresponding figures obtained were 2-8, 2-2, 3-8, 1*4, 3«1. 

 The question arises naturally whether the efficiency of the kidney is indicated by 

 the higher figures, or whether kidneys which under normal conditions give a low 

 urea percentage with MacLean's test can be differentiated further as regards their 

 response to the test under lowered pressure. 



The percentage of urea obtained from the highest of the thi-ee-hourly 

 specimens of urine after the application of MacLean's test to an individual is 



