Parathyroid hormone secretion in the rat: effect of aminophylline (38536)

Administration of aminophylline to intact rats did not cause a change in serum Ca, but did cause a significant increase in serum PTH. Administration of EDTA alone caused hypocalcemia, and a greater increase in PTH than that caused by aminophylline alone. Aminophylline plus EDTA given togeather caused no greater hypocalcemia, but a significantly greater increase in PTH than that by EDTA alone. Therefore, aminophylline increased PTH secretion when given alone, and also enhanced the PTH secretion stimulated by EDTA-induced hypocalcemia in vivo.