Interactions of calcium, magnesium and atropine on exocrine pancreatic secretion in man

Abstract. The effects of the intravenous administration of atropine or magnesium on pancreatic secretion which has been stimulated by secretin and induced hypercal-caemia have been studied in man.
In the presence of secretin (0.5 CU/kg.h) the infusion of Ca²⁺ (0.3 mmol/kg.105 min) resulted in an increase in secretion of enzymes by 100–200%, and in that of Ca²⁺ and Mg²⁺ by 50–100% without affecting fluid and bicarbonate secretion.
The additional injection of atropine (0.5 mg i.v. and 0.5 mg s.c.) were followed by a prompt fall in enzymes but not in Ca²⁺ and Mg²⁺ to the secretin-stimulated values.
The additional infusion of Mg²⁺ (0.12 mmol/kg.45 min) to the Ca²⁺-infusion did not alter the secretion of enzymes, Ca²⁺ or Mg²⁺ compared with the calcium infusion alone.
It is suggested that the hypercalcaemic stimulus depends on an intact innervation of the acinar cells.
In these experiments the secretion of Ca²⁺ and Mg²⁺ seem to originate mainly from extracellular fluxes.