GASTRIC-EMPTYING OF LIQUIDS IN RATS DEHYDRATED BY WATER-DEPRIVATION

The gastric emptying of liquids was investigated in male Wistar rats ( 8 to 10 weeks old, 210-300 g) dehydrated by water deprivation. In this model of dehydration, weight loss, hematocrit and plasma density were significantly higher in the dehydrated animals than in the control gr oups after 48 and 72 h of water deprivation (P<0.05). Three test meals (saline (N = 10), water (N = 10) and a WHO rehydrating solution conta ining in one liter 90 mEq sodium, 20 mEq potassium, 80 mEq chloride an d 30 mEq citrate (N = 10)) were used to study gastric emptying followi ng water deprivation for 24, 48 and 72 h. After 72 h, gastric emptying of the water (39.4% retention) and rehydrating solution (49.2% retent ion) test meals was significantly retarded compared to the correspondi ng control groups (P<0.05, Mann-Whitney test). The 72-h period of depr ivation was used to study the recovery from dehydration, and water was supplied for 60 or 120 min after 67 h of deprivation. Body weight los s, hematocrit and plasma density tended to return to normal when water was offered for 120 min. In the animals supplied with water for 60 mi n, there was a recovery in the gastric emptying of water while the gas tric emptying of the rehydrating solution was still retarded (53.1% re tention; P<0.02, Kruskal-Wallis test). In the group supplied with wate r for 120 min, the gastric emptying of the rehydrating (51.7% retentio n) and gluco-saline (46.0% retention) solutions tended to be retarded (P = 0.04, Kruskal-Wallis test). In this model of dehydration caused b y water deprivation, with little alteration in the body electrolyte co ntent, gastric emptying of the rehydrating solution was retarded after rehydration with water. We conclude that the mechanisms whereby recep tors in the duodenal mucosa can modify gastric motility are altered du ring dehydration caused by water deprivation.