Fenoldopam—but not dopamine—selectively increases gastric mucosal oxygenation in dogs

Abstract

Fenoldopam dose-dependently increased microvascular oxygenation of the gastric mucosa without changing systemic oxygen transport, i.e., this drug acted selectively on the splanchnic mucosa. The increase in gastric mucosal oxygenation was mediated by DA(1)-receptors. In contrast, dopamine markedly increased systemic oxygen transport, but did not affect microvascular oxygenation of gastric mucosa. This lacking effect on gastric mucosal oxygenation was not caused by alpha(1)-mediated vasoconstriction. The regional effects of both catecholamines could not be deduced from systemic hemodynamics and oxygenation.

Pharmacologic Interventions to Improve Splanchnic Oxygenation During Ventilation with Positive End-Expiratory Pressure

“…Moreover in the TEA study [ 15 ] , contrasting our results in earlier studies [ 9,[12][13][14] , restoring preload and thus DO 2 suffi ced to restore splanchnic oxygenation.…”

“…The combined effect of both measures resulted in an increase in m HbO 2 even at low doses of dopamine [ 13 ] . This is in full accordance with our study on the selective dopamine receptor agonist fenoldopam, which preferentially increased m HbO 2 [ 14 ] . Additional measurements with a selective DA 1 -receptor antagonist confi rmed our hypothesis that the DA 1 -receptor is responsible for the benefi cial effects of fenoldopam.…”

“…From our results in the catecholamine studies [12][13][14] we conclude that some vasodilatory action of the drugs could be responsible for their effect on the augmentation of m HbO 2 , for example, dopamine under a 1 -blockade, thus unveiling the vasodilatory potential of the drug, but not dopamine alone improved splanchnic oxygenation [ 13 ] .…”

“…Additional measurements with a selective DA 1 -receptor antagonist confi rmed our hypothesis that the DA 1 -receptor is responsible for the benefi cial effects of fenoldopam. In this setting the dopamine receptor blockade nullifi ed the benefi cial effects of fenoldopam [ 14 ] .…”

Dopamine under α1-blockade, but not dopamine alone or fenoldopam, increases depressed gastric mucosal oxygenation*

“…In this context, dopamine has been used commonly, but its effectiveness has been questioned increasingly (6 -8). Recently, we reported that the synthetic dopaminergics dopexamine and fenoldopam increase gastric mucosal oxygenation under physiologic conditions (9,10). However, catecholamines may elicit different effects under compromised cardiocirculatory conditions, for example, hemorrhage or endotoxemia (7).…”