Potassium in gastric juice under non-steady-state conditions.

In a Heidenhain pouch dog the K(+) concentration of the gastric juice was analyzed after continuous intravenous injections of histamine. The steady states of the secretion rates and the changing over from different steady states were studied. The old observation that the K(+) concentration is independent of the secretion rate in the steady state was confirmed, but it was also found that during an increase of the secretion rate the K(+) concentration in the juice showed a transient increase. In changing the secretion rate to a lower steady level the K(+) concentration showed a similar deviation in the opposite direction before returning to its steady-state level. It is suggested that this phenomenon is due to a loss and uptake of K(+) by the mucosa when stimulation is started or stopped.