The dopamine DA-1 receptor agonist fenoldopam enhances amino-acid-induced hyperemia in dogs.

Abstract

The effect of the dopamine DA-1 receptor agonist fenoldopam on amino-acid-induced glomerular hyperemia and hyperfiltration was evaluated in conscious chronically instrumented dogs. Infusion of either amino acids (L-alanine, 4.1 mg/kg.min; L-proline, 3.2 mg/kg.min; L-serine, 2.9 mg/kg.min) or fenoldopam (0.05 micrograms/kg.min) alone resulted in significant (p < 0.05) increases in renal plasma flow of 85 +/- 41 and 53 +/- 24%, respectively. In dogs infused with both amino acids and fenoldopam, there was a dramatic (143 +/- 27%) increase in renal plasma flow (p < 0.01). This response was significantly greater than either treatment alone. The glomerular filtration rate did not change significantly when fenoldopam was infused; however, it increased to a similar degree when dogs were infused with either amino acids or a combination of fenoldopam and amino acids. The data suggest that fenoldopam either acts synergistically with amino acids to increase renal blood flow or perhaps magnifies the renal functional reserve.