Effects of Synthetic Human Gastrin I on Movements of Water, Electrolytes, and Glucose Across the Human Small Intestine

Abstract

The effect of graded doses (0.125, 0.500, 1.00 and 2.00 mug per kg per hr) of intravenous synthetic human gastrin I (SHG) on jejunal transport of water, electrolytes, and glucose from a glucose-saline solution (solution II) was studied in 12 healthy volunteers, using an intestinal perfusion technique with a proximal occluding balloon. SHG when infused at rates of 0.500 mug per kg per hr or greater significantly reduced water and electrolyte absorption; this effect was linearly related to the dose and reached 40 to 60% of basal absorption (and only 10% for glucose) with the highest dose; insorption of sodium and water were significantly decreased by SHG. In a further group of 9 subjects no effect of SHG (2 mug per kg per hr) was found on jejunal absorption from a mannitol-saline solution (solution I) and on ileal absorption from solutions I and II; in 5 additional subjects, SHG did not decrease jejunal transit time of intraluminal fluid. There was no increase in serum thyrocalcitonin during SHG infusion. It is proposed that SHG selectively depresses the glucose-stimulated sodium transport as suggested by the reduction of the rate of net sodium absorption per micromole of glucose absorbed during SHG infusion. Physiological and pathological implications of these findings are discussed, especially in the light of the circulating levels of immunoreactive gastrin achieved during SHG infusion.