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Putrescine uptake by rabbit intestinal brush-border membrane vesicles
1Unité de Nutrition Humaine et Physiologie Intestinale de l'I.N.R.A., Faculté des Sciences Pharmaceutiques et Biologiques, Paris, France.
Biochemistry International
|July 1, 1992
Summary
Rabbit intestinal cells transport putrescine slowly, independent of sodium and proton gradients. Divalent cations like calcium stimulate uptake, suggesting non-covalent binding to anionic sites.
Area of Science:
- Biochemistry
- Cell Biology
- Physiology
Background:
- Putrescine is a crucial polyamine involved in cellular processes.
- Understanding its transport mechanism in the intestine is vital for nutrient absorption and cellular function.
Purpose of the Study:
- To elucidate the transport mechanism of putrescine across rabbit intestinal brush-border membranes.
- To investigate the factors influencing putrescine uptake, including ion gradients, pH, and cations.
Main Methods:
- Utilized rabbit intestinal brush-border membrane vesicles.
- Measured putrescine uptake over time under various conditions (pH, ion gradients, presence of cations and inhibitors).
Main Results:
- Putrescine transport is a slow, time-dependent process, not driven by Na+ or H+ gradients.
- Uptake is pH-sensitive, decreasing at lower pH.
- Divalent cations (Ca2+, Mg2+, Ba2+) significantly stimulate putrescine accumulation.
- Putrescine uptake is inhibited by other polyamines, indicating specific non-covalent binding to anionic sites.
Conclusions:
- Putrescine transport in rabbit intestinal brush-border membranes is a unique, slow process.
- The mechanism involves non-covalent binding to anionic sites, influenced by divalent cations.
- It does not appear to be a polyamine-H+ exchange or involve covalent binding.