Journals of Gerontology Series A: Biological Sciences and Medical Sciences, Vol 50, Issue 5 M271-M275, Copyright © 1995 by The Gerontological Society of America
Reduced renal response to low-dose dopamine infusion in the elderly
E Mulkerrin, FH Epstein and BA Clark
Charles A. Dana Research Institute, Boston, USA.
BACKGROUND: Increasing age is associated with a number of changes in renal
function, including a diminished capacity to excrete salt and water loads
and an increased susceptibility to acute renal failure. Dopamine is a renal
autocoid important in diuresis and natriuresis and may also serve to
protect against ischemic renal injury. The aim of this study was to assess
the renal response to a low-dose dopamine infusion in healthy young vs
elderly individuals. METHODS: Five healthy young (28 +/- 2 yr) and elderly
(68 +/- 3 yr) subjects underwent evaluation of renal function and blood
pressure before, during, and after a 3-hour infusion of dopamine (1
microgram/kg/min) in the Clinical Research Center of Beth Israel Hospital.
RESULTS: Renal plasma flow, estimated by clearance of para-aminohippurate
clearance, was significantly lower in the elderly than in the young
subjects, but both groups increased estimated renal plasma flow by
approximately 30% during dopamine infusion. Endogenous creatinine clearance
was also significantly lower in the elderly. During dopamine infusion,
creatinine clearance rose significantly only in the young. Both young and
old had a similar natriuretic response to dopamine although urine flow and
free water clearance were significantly lower in the old. Neither group had
significant changes in blood pressure or heart rate. CONCLUSIONS:
Resistance to the actions of dopamine on creatinine clearance in the
elderly may reflect an inability to respond to endogenous dopamine at times
of physiologic stress with resulting susceptibility to azotemia.
