Antidiuresis and natriuresis induced by gastric distension in water-loaded rats

Antidiuretic and natriuretic responses were observed following gastric distension in anesthetized, water-loaded rats. An increase of intragastric pressure to 25, 30, 35, and 40 cm H2O of 2-minute duration respectively elicited 11, 35, 45, and 55% inhibition of water diuresis with concomitant, graded increase of sodium excretion by the kidney. These antidiuretic and natriuretic responses to gastric distension persisted and sustained the same intensity after acute bilateral cervical vagotomy, indicating that the sensory input conveyed from the gastric mechanoreceptors to central nervous system during gastric distension should involve afferent fibers other than vagus nerve. Rats with diabetes insipidus (D1) produced by hypothalamic lesions were also tested, but neither antidiuresis nor natriuresis in response to gastric distension was observed in these D1 rats whose neurohypophysis contained little antidiuretic hormone (ADH). In conclusion, gastric distension may induce liberation of ADH and probably other neurohypophysial hormone which affects renal handling of sodium and water in anesthetized, water-loaded rats.