Role of kidney dopamine in the natriuretic response to volume expansion in rats.

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Abstract
It has been postulated that endogenously produced dopamine (DA) may play a role in the regulation of renal sodium excretion. In the present study, experiments were designed to test the hypothesis that acute volume expansion with isotonic sodium chloride stimulates the production of DA within the kidney, which in turn acts on specific DA1 receptors to promote sodium excretion. In pentobarbital-anesthetized rats, acute volume expansion over a period of 1 hour evoked a pronounced increase in urine output and urinary sodium excretion. These diuretic and natriuretic effects were not accompanied by any significant changes in blood pressure or heart rate. However, there was a significant elevation in central venous pressure and a transient rise in glomerular filtration rate. The natriuretic and diuretic response was accompanied by a significant increase in urinary DA excretion, and this effect was clearly dissociated from the rise in glomerular filtration rate. In a separate group of rats, the effects of acute v...