Suppressor calcium infusion raises plasma atrial natriuretic peptide concentrations in humans

1. Calcium was infused in normal subjects in subpressor dosage to examine the effects of raised calcium levels on atrial natriuretic peptide (ANP) concentrations. 2. Calcium infusion progressively raised serum ionized and total calcium concentrations significantly, without raising mean arterial pressure or heart rate. 3. Plasma ANP concentrations increased significantly by 5 min of infusion and increased further by 15 min (approximately 40%) to levels which were maintained to 60 min. 4. Urinary sodium excretion increased by 140% during calcium infusion. 5. Calcium may affect secretory as well as contractile functions of the atrial myocyte.