Submitted on February 7, 2008
Accepted on April 4, 2008
The natriuretic and diuretic response to dopamine is maintained during rat pregnancy
Jennifer M Sasser1* and Chris Baylis2
1 Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida, United States; , United States
2 Physiology and Functional Genomics, University of Florida, Gainesville, Florida, United States
* To whom correspondence should be addressed. E-mail: jmsasser{at}ufl.edu.
During pregnancy, there is a marked plasma volume expansion due to renal sodium retention. Pregnant rats exhibit a blunted response to natriuretic stimuli that signal via cGMP, and expression and activity of the cGMP phosphodiesterase PDE5 are upregulated in the inner medullary collecting duct during pregnancy. Here, we tested the hypothesis that the natriuretic response to a cAMP agonist, dopamine, is maintained during pregnancy. Anesthetized pregnant (day 16) and age-matched virgin Sprague-Dawley rats were used to determine if dopamine-cAMP-mediated natriuresis remains intact in pregnant rats. Blood pressure, renal clearances of inulin and p-aminohippuric acid, and excretion of sodium were measured during baseline and dopamine infusion periods. Pregnant rats had a lower blood pressure and hematocrit at baseline than their age-matched virgin counterparts. Dopamine infusion decreased blood pressure and increased glomerular filtration rate and renal plasma flow in virgin but not pregnant rats. Dopamine infusion also increased urine volume, sodium excretion, and the fractional excretion of sodium to a similar extent in virgin and pregnant rats. These results indicate that a cAMP mediated natriuresis and diuresis (stimulated by dopamine) persists in pregnant rats.
