ASYNCHRONY IN CIRCADIAN-RHYTHMS OF GASTRIC FUNCTION IN THE RAT - A MODEL FOR GASTRIC-MUCOSAL INJURY

A model for gastric mucosal injury is proposed in which a key pathogen etic event is the disruption in the normal relationships among several circadian rhythms of gastric function. In the rat a circadian rhythm in acid secretion was found to be out of phase with a circadian rhythm in gastric pepsin secretion, another aggressive factor, and several m ucosal defensive factors (mucus and bicarbonate efflux and tissue pros tacyclin content). Gastric corpus mucosal blood flow circadian pattern s paralleled the rhythmicity in acid secretion and, therefore, was out of phase with the other measured mucosal defensive factors. Thus, gas tric mucosal defense was maintained by different mechanisms over the 2 4-hr cycle. During the dark phase, when this species was active and wh en acid secretion was highest, enhanced damage by topical acidified as pirin was documented, despite increased mucosal blood flow. Natural as ynchrony in circadian rhythms of gastric function can be protective of gastric mucosal integrity but disruption of this circadian interplay of gastric aggressive and defensive factors could theoretically lead t o greater vulnerability to damage. In the human, a circadian rhythm in basal gastric acidity has been described but no information exists as to the possibility of similar rhythmic variation in other gastric fac tors (aggressive and defensive) and possible disruption of these rhyth ms in disease.