Reduction of serum parathyroid hormone levels during sympathetic stimulation in man.

The parathyroid glands contain sympathetic nerve endings and the parathyroid cells are endowed with beta-adrenergic receptors. The physiological role of the sympathoadrenal system for the secretion of parathyroid hormone (PTH) has, however, not been clarified. Using the technique of lower body negative pressure (LBNP), which is an established method to achieve sympathetic nerve activation, it was found in 17 healthy subjects that the venous serum levels of PTH were reduced by 7% within 20 min [from 0.79 +/- 0.12 (SD) to 0.74 +/- 0.11 arbU/l, p less than 0.01, paired t test]. The reduction corresponds to 30% of the maximal suppressibility of PTH by induced hypercalcemia or following parathyroidectomy when studied with the same PTH assay and with the short time period involved. After cessation of LBNP the PTH levels returned to baseline within 20 min. There were no concomitant changes of the plasma ionized calcium concentrations. The findings are compatible with a role for the sympathetic nervous system in the physiologic regulation of the secretion of PTH.