Nerve involvement in fluid transport in the inflamed rat jejunum.

Abstract

Net fluid transport was measured in denervated jejunal segments of rats infected with larvae of Nippostrongylus brasiliensis. On days 6-9 after nematode inoculation, when the jejunal segment exhibited macroscopic and microscopic signs of inflammation, net fluid absorption was noticeably attenuated compared with control, and in eight of 26 experiments a net fluid secretion was seen. To determine whether enteric nerves participated in the response, intravenous hexamethonium (10 mg/ kg body weight) was given or lidocaine (1% solution) was placed on the serosa of the intestinal segment. Both drugs significantly reduced fluid secretion or increased fluid absorption. The This study was designed to investigate further the relationship between inflammation and fluid transport in the small intestine of the rat. For this purpose rats were inoculated with Nippostrongylus brasiliensis by injecting the parasites subcutaneously. On day 3 the nematodes reach the small intestine and on days 6-8 an inflammatory response in the jejunum is seen. Ten to 12 days after inoculation, the worms are expelled from the small intestine and the inflammatory response fades away. Fluid transport was measured in vivo in rats before and after expulsion of the parasite and the possible involvement of ENS in the response was tested pharmacologically. Methods ANIMALSSprague-Dawley rats (Alab AB, Stockholm, Sweden) weighing 300-400 g were given a subcutaneous injection of 6000 larvae of Nippostrongylus brasiliensis in 0 5 ml saline. Rats were housed in standardised environmental conditions (22°C, 60% humidity, light 6-00-18.00 hours). The animals were studied on days 6-9 or 11-14 after being injected with larvae.ANESTHESIA AND OPERATIVE PROCEDURES Anaesthesia was induced by mebumal (60 mg.kg-1 body weight) and maintained with chloralose (100 mg.kg-1 bw) as a bolus plus 20 mg.h-l.kg-1 body weight as an infusion.A tracheotomy was performed and a tracheal cannula was inserted to maintain a free airway. Catheters were inserted into the femoral artery and vein for blood pressure recordings and drug administration, respectively. To prevent acidosis due to the operative trauma an infusion of a glucose-bicarbonate solution (see below) was given intra-arterially at a rate of 0 03 ml.min-l. A Statham pressure transducer (Model P23AC) was connected to the arterial catheter and arterial pressure was continuously recorded on a Grass polygraph.The abdomen was opened by midline incision. A 5 to 10 cm long segment of the jejunum was selected. In the experiments performed on days 6-9 after injecting the larvae, the part of the jejunum with the most severe signs of inflammation was selected for the experiment. The remainder of the small intestine and the colon were removed. All nerves in the tissues around the superior mesenteric artery were cut, thereby accomplishing denervation of the extrinsic autonomic nervous supply to the intestinal segment.The rat was placed on a thermistor controlled operating table. The rat, except for its head and 1526 on 9 May 20...

Enteric infections, diarrhea, and their impact on function and development

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Cholinergic regulation of epithelial ion transport in the mammalian intestine

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Involvement of nerves and calcium channels in the intestinal response to Clostridium difficile toxin A: an experimental study in rats in vivo

“…Hexamethonium (10 mg/kg body weight) given as a single dose intravenously returned fluid transport to control (5 (18) μl/min/100 cm 2 ; p<0.05) within minutes. The effects of hexamethonium have been tested repeatedly on control segments in this laboratory (for example, see Cassuto and colleagues23, Karlström and colleagues,24and Jodal and colleagues25). Fluid transport was increased in the absorptive direction.…”