Lack of effect of parathyroid hormone on calcium homeostasis in rat platelets

The in vitro effects of parathyroid hormone on Ca2+ handling by fura-2 loaded rat platelets were studied. The incubation of these platelets with rat parathyroid hormone (1-34) for 10 min had no effect on intracellular fura-2 metabolism or [Ca2+]i in the resting state. The [Ca2+]i response to 0.1 U/mL thrombin was unaffected by preincubation with parathyroid hormone in the presence or absence of extracellular Ca2+. Furthermore, the recovery rate of [Ca2+]i after the thrombin-induced peak in Ca(2+)-depleted media was not altered with parathyroid hormone. These data indicate that parathyroid hormone may not have a significant effect on Ca2+ homeostasis in rat platelets in unstimulated and stimulated conditions.