Acute intracranial hypertension-induced inhibition of gastric emptying: evaluation in conscious rats

To study the effect of raised intracranial pressure (ICP)-induced alteratio ns in gastric emptying, and their modulation by pharmacological interventio ns, an experimental model was standardized in rats. A test meal of methylce llulose and phenol red was administered intragastrically. ICP was raised to 40, 60 and 80 mmHg by connecting a buffered saline pressure head to an int racerebroventricular (i.c.v.) cannula. Gastric emptying was estimated after killing the animals, from the residual stomach phenol red content. Inhibit ion of gastric emptying was observed when ICP was raised, the maximum being at 80 mmHg ICP (percent gastric emptying 26.5% +/- 2.8 vs. 83.4 +/- 4.7 in sham-ICP). Pretreatment with clonidine, prazosin or ondansetron did not mo dify the raised ICP induced inhibition of gastric emptying. Cisapride was i neffective at 1 mg/kg but caused a partial reversal at the 5- and 10-mg/kg doses (46.9 +/- 3.1% and 42.6 +/- 4.0%, respectively). Carbachol at a lower dose of 0.1 mg/kg i.p., produced a greater reversal (78.3 +/- 6.0%) than d id the high dose (52.8 +/- 4.1). Bretylium partially reversed the inhibitio n of gastric emptying (45.7 +/- 4.3%). The protective effect of carbachol a nd cisapride suggests that suppression of vagal activity due to increased I CP may play an important role in the inhibition of gastric emptying due to intracranial hyper-tension. (C) 1999 Elsevier Science B.V. All rights reser ved.