Prostaglandins are lipid molecules synthesized by cyclooxygenase that affect the response of mammalian colonic mucosa to disease.1–4 Higher concentrations of PGs are found in inflamed5 and cancerous4,6 colonic tissue than in surrounding normal tissue. Prostaglandins stimulate secretion in the colon, which can result in diarrhea.7 Prostaglandin E2 is a primary secretagogue and is probably the principal mediator among PGs in the mammalian colon.8,9 Nonsteroidal anti-inflammatory drugs, such as indomethacin, block the synthesis of PGs by inhibiting cyclooxygenase. Indomethacin can reduce PGE2-mediated secretory diarrhea caused by rectal villous adenoma in humans10 and can inhibit PGE2-induced colorectal carcinogenesis in rats11 and in human cells in vitro.12
It has been suggested in some reports13,14 that there are regional differences in ion transport within the large intestine of mammals; however, studies15–22 of canine colonic mucosa have exclusively used the proximal portion of the colon. Therefore, the purpose of the study reported here was to determine ex vivo whether there are regional differences in ion transport and secretory response to exogenous PGE2 and indomethacin in canine colonic mucosa.
Area under the curve
Change in short-circuit current
Change in potential difference
Model U-9500, MRA International, Naples, Fla.
Model DVC1000, World Precision Instruments Inc, Sarasota, Fla.
BIOMOL Research Laboratories, Plymouth Meeting, Pa.
Sigma Chemical Co, St Louis, Mo.
SAS, version 6.12, SAS Institute Inc, Cary NC.
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