|Budget Amount *help
¥3,600,000 (Direct Cost : ¥3,600,000)
Fiscal Year 1994 : ¥1,300,000 (Direct Cost : ¥1,300,000)
Fiscal Year 1993 : ¥2,300,000 (Direct Cost : ¥2,300,000)
The origin of dopamine in urine was investigated using rats nephrectomized, denervated the renal nerve and treated with carbidopa, an inhibitor of DOPA decarboxylase. The free dopamine excreted in urine is derived from renal tubular dopamine, which is synthesized at proximal tubules and regulates both natriuresis and diuresis. The conjugated dopamine excreted in urine is derived from renal filtrated dopamine, which is originated from the conjugated dopamine in plasma. As the plasma conjugated dopamine is filtrated at glomerulus, the plasma conjugated dopamine elevates in the patients with impaired renal function. Using these parameters of urinary free dopamine, urinary conjugated dopamine and plasma conjugated dopamine, it is possible to evaluate the renal function. We investigated the usefulness of the urinary level of dopamine as a marker of renal function, especially of tubular activity. We determined the correlations between the urinary level of free dopamine and a number of established markers of renal function in patients with chronic glomerulonephritis and healthy volunteers. The urinary level of free dopamine was negatively correlated with the serum level of creatinine and the urinary levels of alpha1-and beta2-microglobulins, and was positively correlated with urinary level of creatinine, urea nitrogen, potassium and inorganic phosphorus. Findings suggest that the urinary level of dopamine is an index of renal functions and that measurements of the urinary level of free dopamine are useful for evaluating renal impairment.