THE INFLUENCE OF BICARBONATE AND PHOSPHATE ON THE MOVEMENTS OF SURVIVING INTESTINE

¹ Rowett Institute, Aberdeen

The effects of change in the bicarbonate and phosphate content of Tyrode's fluid at 38° on the pendular movements of surviving segments of ileum from rabbits which had fasted for fifteen hours are recorded. The pH of the fluid was kept constant, or its effects controlled.

Sodium bicarbonate, independently of its alkalinity or its buffering action, beneficially affects the whole contractile process, its regularising action being the most outstanding. The results are immediate and reversible. In its absence the effect of Ca is fundamentally altered; but those of K and Mg are unchanged.

The immediate effects of phosphate proved to be variable, but at pH 7.4 and above they were, on the whole, of a regularising nature, and independent of its pH or buffering effects. Concentrations of phosphate above or below 0.005 per cent. NaH₂PO₄ had, after numerous changes over several hours, a harmful effect. The actions of Ca, K, or Mg are unaltered by the absence of phosphate.

The opinion is expressed that the actions of bicarbonate and phosphate are attributable to the anions HCO'₃ and HPO'₄ respectively.