The reduced sodium absorption during high salt intake in young rats requires endogenous dopamine action. Net colonic potassium absorption in young rats is five times higher than in adult ones. The majority of colonic net potassium absorption occurs in the distal part of the colon. Using different approaches this study shows that apically located transporters which reabsorb potassium are upregulated in the infant rat while secreting basolateral transporters are upregulated in adult rats. Angiotensin II induces potassium secretion in rat distal colon.
Boys have a significantly higher amount than girls.
In summary, these studies of ion transport in the gastrointestinal tract show new mechanisms that ensure proper regulation of sodium, potassium and hydrogen transport during development. We have found that glucorticoids and dopamine have specific actions on ion transport during early development. In addition we have found that angiotensin II regulates colonic potassium transport in a complex manner.