Fenoldopam mesylate, a dopamine-1 receptor agonist, has dose-and species-dependent effects on hemodynamics and renal function. The effects of this drug in normotensive neonatal foals have not been reported.Hypothesis:
Two doses of fenoldopam would result in distinct changes in the systemic circulation, urine output, and creatinine clearance of neonatal foals.Animals:
Six Thoroughbred foals.Methods:
Each foal received 2 dosages of fenoldopam (low dose, 0.04 μg/kg/min; high dose, 0.4 μg/kg/min) and a control administration of saline, in a masked, placebo-controlled study.Results:
High-dosage fenoldopam had no effect on renal function but caused a significant increase in heart rate and decrease in mean, systolic and diastolic arterial blood pressure compared with saline. Low-dosage fenoldopam had no effects on systemic hemodynamics, significantly increased urine output, and had no significant effect on creatinine clearance or the fractional excretions of sodium, potassium, or chloride compared with saline.Conclusions and Clinical Importance:
These data suggest that high-dosage fenoldopam increases heart rate, decreases arterial blood pressure, and has no significant effects on renal function, whereas low-dosage fenoldopam has no significant effects on systemic hemodynamics while increasing urine output. This contrast is unique to this species and warrants further investigation.