Effect of Intravenous Dopamine Infusion on Intramural Blood Flow Distribution and Fluid Absorption in the Feline Small Intestine

Abstract

The aim of the study was to investigate the effects of dopamine on the intestinal mucosal blood flow and transport function. Dopamine was infused intravenously at 20 μg × kg^-1 × min^-1 in anesthetized cats. Total and intramural blood flow in an isolated jejunal segment was measured by a combined drop-flow and ⁸⁵Kr clearance technique. Net fluid transport was recorded by two independent perfusion methods. Unidirectional sodium transport was estimated from luminal ²²Na disappearance. Dopamine induced a pronounced mucosal vasodilatation up to 400% of control values. Concomitantly, net fluid and sodium absorption increased by 50%. The effect on sodium transport was due to a pronounced decrease in tissue-to-lumen sodium flux, a pattern similar to the one seen on (α-adrenergic stimulation. The effect of dopamine on blood flow was unaffected by phentolamine. 1 mg × kg^-1, whereas the absorptive response was abolished. The findings indicate that dopamine induces a mucosal vasodilatation via one mechanism (possibly dopaminergic) and enhances fluid transport via another mechanism, probably α-adrenergic.

Key words:

• α-Adrenergic
• dopamine
• intestinal absorption
• intestinal blood flow