Dopamine and dopaminergic agonists relax renal arteries via direct actions in vascular D1 dopamine receptors. Fenoldopam is a D1 selective agonist. They increase renal blood flow and glomerular filtration rate. They are used primarily for other purposes, diuretic actions are more a side-effect than an indication. There is the potential for inadvertent poisoning.
Dogs are especially sensitive to methyl xanthine toxicity.
Antagonism of A1 receptors in the kidney also protects tubules from nephrotoxins that cause acute tubular necrosis. Specific A1 antagonists, e.g., FK453, are being developed. Water is a simple common sense approach to flushing the kidneys. It maintains urine flow and is of value in eliminating and diluting out nephrotoxins that accumulate in the kidney. Development of water channel blockers in the proximal tubule is ongoing.