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Dopaminergic receptor-mediated effects in the mesenteric vasculature and renal vasculature of the chronically instrumented newborn piglet.

Abstract：

OBJECTIVE:To determine the effects of stimulation of vascular dopaminergic receptor subtype 1 (dopamine-1) receptors in the renal and mesenteric vascular beds of a neonatal model. DESIGN:Prospective, unblinded, dose-response evaluation in an awake animal. SETTING:University research laboratory. SUBJECTS:Thirty newborn piglets, obtained and instrumented at 1 to 3 days of age and studied 48 hrs later. INTERVENTIONS:Animals were chronically instrumented with transit time ultrasound flow probes around the left renal and superior mesenteric arteries. They were then intravenously infused with either dopamine (2 to 32 micrograms/kg/min) or fenoldopam (1 to 100 micrograms/kg/min), which is a selective agonist of the dopamine-1 receptor. MEASUREMENTS AND MAIN RESULTS:Blood pressure was only significantly increased by the highest infusion rate of dopamine (32 micrograms/kg/min), from a mean of 78 mm Hg at baseline to 87 mm Hg. Mesenteric and renal vascular resistances were unchanged by dopamine at any dose. Dopamine at 32 micrograms/kg/min decreased renal blood flow by 16.6 +/- 19.6 (SD) % and increased renal vascular resistance by 39.6 +/- 41.1% (p < .05). Mesenteric blood flow increased by 15% at 32 micrograms/kg/min (p < .05) but mesenteric vascular resistance was not affected by dopamine. Fenoldopam reduced blood pressure at infusion rates of 5, 10, and 100 micrograms/kg/min. Fenoldopam had no effect on renal vascular resistance at any dose. Fenoldopam reduced mesenteric vascular resistance at 5 micrograms/kg/min and at all higher doses. CONCLUSIONS:These data demonstrate the absence of dopaminergic receptor-mediated vasodilation in the porcine neonatal renal vascular bed. In the mesenteric artery, dopamine-1 receptor-mediated vasodilation may be obtained. Dopamine itself, probably because of stimulation of other receptors, causes renal artery vasoconstriction and does not increase superior mesenteric artery blood flow.

journal_name

Crit Care Med

journal_title

Critical care medicine

authors

Pearson RJ,Barrington KJ,Jirsch DW,Cheung PY

doi

10.1097/00003246-199610000-00018

subject

Has Abstract

pub_date

1996-10-01 00:00:00

pages

1706-12

issue

eissn

0090-3493

issn

1530-0293

journal_volume

pub_type

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Dopaminergic receptor-mediated effects in the mesenteric vasculature and renal vasculature of the chronically instrumented newborn piglet.