Cholera-induced mucin secretion from rat intestine: lack of effect of cAMP, cycloheximide, VIP, and colchicine
| Autor: | M. Laburthe, N. Fleming, R. Crowther, N. Roomi, Janet F. Forstner |
|---|---|
| Rok vydání: | 1984 |
| Předmět: |
medicine.medical_specialty
Cholera Toxin Physiology Secretory Rate Vasoactive intestinal peptide Biology Cycloheximide In Vitro Techniques medicine.disease_cause chemistry.chemical_compound Cholera Theophylline Physiology (medical) Internal medicine medicine Cyclic AMP Animals Secretion Mannitol Intestinal Mucosa Goblet cell Hepatology Mucin Gastroenterology Isoproterenol Mucins Intestinal epithelium Rats Endocrinology medicine.anatomical_structure chemistry Bucladesine Vibrio cholerae Colchicine Vasoactive Intestinal Peptide |
| Zdroj: | The American journal of physiology. 247(2 Pt 1) |
| ISSN: | 0002-9513 |
| Popis: | Purified cholera enterotoxin (20-50 micrograms) and dialyzed cholera filtrate (50-125 mg) increased net glycoprotein synthetic and secretory rates in rat intestinal epithelium. Specific goblet cell mucin secretion was increased 5- to 10-fold. However, other agents that increase intestinal cAMP and accelerate glycoprotein synthesis did not enhance mucin secretion. This was true for dibutyryl cAMP (10(-3) and 10(-2) M) with or without theophylline (10(-3) M) and isoproterenol (10(-4) M) with or without dibutyryl cAMP (10(-3) M). Hyperosmotic mannitol (450 mosmol/l), which increases fluid secretion but does not affect cAMP, and vasoactive intestinal peptide (2 X 10(-7) M), which increases both fluid secretion and cAMP, both failed to increase mucin secretion, implying that fluid "washout" of mucin adherent to the mucosal surface is not responsible for cholera-induced mucin secretion. Cycloheximide, an inhibitor of cholera diarrhea in vivo (20 mg/kg) or in vitro (1 mM), effectively abolished [3H]leucine incorporation into protein but did not affect cholera-induced mucin secretion. Colchicine (10-50 mg/kg) given to block microtubule assembly was similarly without effect on mucin secretion. These findings suggest that there is a dissociation of electrolyte/fluid and mucin secretory processes and cast doubt on the widely accepted notion that all cholera effects are mediated via the well-known adenylate cyclase-cAMP mechanism. |
| Databáze: | OpenAIRE |
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