The Effect of Metoclopramide Administration on Electrolyte Status and Activity of Renin-Angiotensin-Aldosterone System in Premature Infants

Abstract

ABSTRACT. The present study has been carried out to define whether endogenous dopamine contributes to the regulation of renal sodium handling and the function of the renin-angiotensin-aldosterone system in low birth weight premature infants. Twelve premature infants with mean birth weight of 1420 g and mean gestational age of 29.2 wk were given metoclopramide (MTC) in a dose of 0.1 mg/ kg/day to treat delayed gastric emptying, regurgitation, and abdominal distension at the age of 17-23 days. Infants were kept on either a low (2-3 mEq/kg/day) or high (4-7 mEq/kg/day) sodium diet to modulate activity of RAAS. Prior to and after a 3-day period of M T C administration, blood samples were taken, and in six male infants 24-h urine collections were made to determine plasma and urine electrolytes, plasma renin activity, plasma aldosterone concentration, and urinary aldosterone excretion. We demonstrated that plasma sodium and potassium concentrations and plasma renin activity were not altered by MTC. O n the other hand, in response to MTC, there was a significant increase in urinary sodium excretion (1.8 + 0.3 versus 2.3 + 0.3 mEq/kg/day) and a decrease in potassium excretion (1.2 + 0.2 versus 0.8 + 0.1 mEq/kg/day); plasma aldosterone concentration and urinary aldosterone excretion decreased significantly from initial values of 2101 + 274 pg/ ml and 2.91 + 0.52 pg/day to 1500 + 207 pglml ( p < 0.01) and 2.21 2 0.43 pg/day ( p < 0.01), respectively, after M'TC. These alterations were independent of the pretreatment hormone levels. We conclude that in low birth weight premature infants endogenous dopamine has no influence on plasma renin activity and enhances rather than inhibits aldosterone production and renal tubular sodium reabsorption. (Pediatr Res 19: 912-915, 1985) Abbreviations DA, dopamine RAAS, renin-angiotensin-aldosterone system PRA, plasma renin activity pAldo, plasma aldosterone concentration UAE, urinary aldosterone excretion MTC, metoclopramideIn recent years several lines of evidence have suggested a role of DA in thc regulation of renal sodium excretion and the involvement of dopaminergic mechanisms in the control of the RAAS system. Urinary DA excretion has been demonstrated to correlate positively with sodium intake and urinary sodium excretion ( 1-4), and a dose-dependent increase in urinary sodium excretion has been reported after DA administration (5-7) suggesting a natriuretic role for DA. Moreover, DA has been shown to increase renin release (8-lo), to inhibit angiotensin-induced aldosterone production (1 1-13), and to enhance the renal response to aldosterone (14).Very few data are available on the interactions among dopaminergic mechanisms, sodium homeostasis, and the RAAS during the neonatal period. It has been observed, however, that DA given to sick premature infants in a dose of 0.5-4.0 pg/min/kg increased sodium and water diuresis (15) and enhanced PRA, but did not cause significant alteration in pAldo (16). In an attempt to define the relationship between endogenous DA, renal sodium exc...

Effect of Metoclopramide Therapy on Arginine Vasopressin Excretion and Renal Water Handling in Premature Infants

“…On the other hand, sodium depletion was found to be associated with a high rate of urinary DA excretion which could be re duced by giving supplemental sodium [2], Moreover, administration of mctoclopramide (MTC), a specific DA antagonist, re sulted in a significant increase of renal so dium excretion and in a fall of daily aldoste rone excretion, indicating that, in contrast to the general view, the physiological role of DA in premature infants is to enhance renal tubular sodium rcabsorption cither directly or indirectly through stimulation of aldoste rone production [3], No data are available on the pathomcchanism of the DA-induccd water diuresis. It has not been established whether the in creased rate of renal water excretion during DA therapy is only a pharmacological effect of DA or whether under physiological condi tions DA also enhances renal water excre tion.…”