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NO chi generation by cultured small intestinal epithelial cells
A U Dignass1, D K Podolsky, D Rachmilewitz
1Gastrointestinal Unit, Boston, USA.
Digestive Diseases and Sciences
|September 1, 1995
Summary
Small intestinal epithelial cells generate nitric oxide (NO) when stimulated by cytokines, growth factors, and bacterial products. This NO generation, influenced by various factors, plays a role in intestinal functions.
Area of Science:
- Gastroenterology
- Immunology
- Cell Biology
Background:
- Nitric oxide (NO) plays a crucial role in intestinal physiology and pathophysiology.
- Intestinal epithelial cells (IECs) are key players in mucosal immunity and barrier function.
- Understanding the regulation of NO production by IECs is essential for comprehending intestinal homeostasis.
Purpose of the Study:
- To investigate the effects of various stimuli on nitric oxide (NO) generation by small intestinal epithelial cells (IEC-6 cells).
- To determine the role of NO synthase (NOS) activity in IEC-6 cells.
- To explore potential mechanisms underlying the biological effects of IEC-derived NO in the intestinal tract.
Main Methods:
- IEC-6 cells were cultured and treated with calcium ionophore (CaI), NOS inhibitors (L-NAME, L-NNA), cytokines, growth factors, mitogens, and bacterial products (LPS).
- NO generation was quantified in cell culture supernatants.
- NO synthase activity was measured using the [14C] arginine conversion to citrulline assay.
- NADPH dependence of NOS activity was assessed.
Main Results:
- NO generation was higher in subconfluent IEC-6 cells compared to confluent cultures, indicating contact inhibition.
- Calcium ionophore (CaI) significantly increased NO generation, while L-NAME and L-NNA inhibited it.
- Bacterial products (LPS), cytokines (IL-1β, IL-2, IL-8, IFN-γ, TNF-α), growth factors (EGF, TGF-α, bFGF), and mitogens (PHA) significantly enhanced NO generation.
- IEC-6 cells exhibited NADPH-dependent NO synthase activity.
Conclusions:
- Intestinal epithelial cells (IEC-6) are capable of generating nitric oxide (NO) in response to various stimuli.
- Cytokines, growth factors, mitogens, and bacterial products can significantly modulate NO production by IECs.
- Stimulation of NO generation in intestinal epithelial cells represents a potential mechanism contributing to their diverse functions within the intestinal tract.