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Morphine-neural interactions on canine intestinal absorption and blood flow
British Journal of Pharmacology
|February 1, 1984
Summary
Morphine affects intestinal absorption differently depending on administration. Intra-arterial morphine blocks nerve inhibition, while intraluminal morphine enhances sodium and water absorption via direct or intrinsic nerve pathways.
Area of Science:
- Gastroenterology
- Pharmacology
- Physiology
Background:
- The gut's nervous system influences sodium (Na) and water (H2O) absorption.
- Morphine's effects on intestinal function are complex and depend on administration route.
Purpose of the Study:
- To investigate the impact of intra-arterial and intraluminal morphine sulfate on intestinal Na and H2O transport.
- To determine the role of extrinsic nerves and blood flow in morphine's effects on the ileum.
Main Methods:
- Experiments were conducted on denervated and innervated ileal segments of fed dogs.
- Unidirectional Na and H2O fluxes were measured using isotopes (3H2O, 22Na).
- Blood flow was assessed using 3H2O clearances during various morphine infusions.
Main Results:
- Net Na and H2O absorption decreased over time in innervated segments but remained stable in denervated segments.
- Intra-arterial morphine prevented absorption decline in innervated segments by increasing absorptive fluxes.
- Intraluminal morphine enhanced Na and H2O absorption in both innervated and denervated segments.
Conclusions:
- Intra-arterial morphine appears to inhibit an antiabsorptive neural effect from extrinsic nerves.
- Intraluminal morphine promotes intestinal absorption, potentially through direct action or intrinsic nerves.
- Absorptive site blood flow is linked to Na absorption, with varying responses to morphine administration routes.