The effect of bilateral ligation of the parotid duct on phosphorus, sodium and potassium metabolism and acid-base balance in the goat.

Abstract

1. The bilateral parotid ducts were ligated in five goats to study the influence of parotid salivation on phosphorus, sodium and potassium homeostasis and acid-base balance. The compositions of urine, feces, blood and rumen fluid were determined during the control period and for four weeks after ligation. 2. The parotid duct ligation caused an increase in urinary phosphorus excretion and plasma inorganic phosphorus level. Fecal phosphorus output decreased, but total phosphorus output in urine and feces changed little. It seems likely that the increase in plasma and urinary phosphorus level and the decrease in fecal phosphorus output may have been caused by the decrease in phosphorus recycling via parotid salivation. Urine pH became acidic and urinary titratable acid excretion increased after ligation. 3. Urinary sodium and chloride excretion decreased transiently by ligation and then returned to the initial level. Urinary potassium excretion did not change after ligation, except for a few days. Fecal sodium and potassium output was not affected. 4. Sodium and inorganic phosphorus levels of rumen fluid decreased rapidly by ligation and then tended to return. to the initial levels. Duct ligation caused a small increase in potassium level and little change in pH of rumen fluid. 5. Plasma bicarbonate, sodium, potassium and chloride levels and blood pH scarcely changed. 6. In ruminants, phosphorus homeostasis seemed to have a close correlation to the parotid function, since a decrease in parotid salivation caused a change in phosphorus homeostasis. It was assumed, however, that sodium and potassium homeostasis might not be influenced so much by the ligation of the parotid duct.