Gastric branch vagotomy and gastric emptying during and after intragastric infusion of glucose

The effect of gastric branch vagotomy (GVX) on the gastric emptying of glucose was evaluated during two phases of emptying control: as the stomach fills and in the postload period. GVX and control rats received a series of intragastric glucose infusions (1.0 ml/min) through indwelling gastric fistulas. In experiment 1, gastric samples were withdrawn either immediately after the offset of 9- or 18-min infusions of 12.5% glucose or at various times up to 36 min postinfusion. In experiment 2, samples were withdrawn either immediately or 30 min after termination of 12-min infusions of 12.5 or 25% glucose. After gastric fill, glucose solute emptying rate was stable over time, not influenced by concentration doubling, and, surprisingly, not affected by GVX. During gastric fill, solute emptying rate doubled with concentration in both GVX and control rats. For each concentration, however, glucose emptied during fill at almost twice the rate in GVX compared with control rats. This accelerated emptying of glucose during fill in GVX rats is consistent with a gastric vagal contribution to inhibitory mechanisms (e.g., receptive relaxation) that operate as the stomach fills under normal conditions. The absence of a GVX effect on emptying after fill suggests either that gastric branch vagal efferents play little role in feedback inhibitory control of glucose emptying under normal conditions or that other systems compensate for the function previously served by vagal gastric branch efferents. Further work is required to address the possible role of the gastric vagus in feedback control of gastric emptying when nutritive fluids other than glucose are delivered.