1976 Volume 13 Issue 3 Pages 193-197
The response of plasma renin activity (PRA) to intravenous administration of Furosemide (Fsm) (0.5mg/Kg) was determined in 6 normotensive young adults (Group I), 14 normotensive aged subjects (Group II) and in 31 hypertensive aged subjects (Group III).
PRA before Fsm administration were 1.49±0.97ng/ml/hr (M±SE) in Group I, 1.07±0.23 in Group II and 1.10±0.85 in Group III, respectively. No significant difference in PRA was noticed among the three groups. PRA of 20 minutes after Fsm administration were 6.76±1.1 in Group I, 1.46±0.3 in Group II and 1.43±0.97 in Group III respectively. PRA of Group I significantly exceeded those of Groups II and III. (P<0.01) PRA increases significantly (P<0.01) after Fsm administration in Group I, but not in Group II and III.
In order to compare the diuretic effect of Fsm in young adults and aged subjects, 4 hours' urine volume, before and after Fsm administration, and urinary excretion of sodium for corresponding periods were compared between 6 young adults and 21 aged subjects.
Urinary volume in young adults was 150.6±5.4ml/4hrs (M±SE) before Fsm and 1155.3±114.5 after Fsm. Urinary volume in aged subject was 269.0±36.0 and 770.0±80.8, respectively. The increase of sodium excretion with Fsm was also less in aged subjects than in young adults.
The diuretic effect of Fsm in young adults was significantly larger than that in aged subjects (P<0.05).
From these results, it was concluded that 1) PRA values at rest were not significantly different among normotensive young adults, normotensive and hypertensive aged subjects, 2) the response of PRA to Fsm in normotensive young adults was significantly larger than those in normotensive and hypertensive aged subjects and 3) the diuretic effect of Fsm in aged subjects was less marked than that in young adults.
