Plasma and saliva substance P levels: the effects of acute pain in pregnant and non-pregnant women.

Substance P like immunoreactivity (SPLI) and total protein (TP) concentrations in plasma and saliva were measured in 80 healthy female patients divided into the following four groups: women in group 1 were not pregnant and they were awaiting tubal ligation; women in group 2 were not pregnant but they experienced acute postoperative pain following hysterectomy; women in group 3 were pregnant and were awaiting elective cesarean section; and women in group 4 were in active labor and experienced acute labor pain. Pain intensity was assessed using verbal Likert pain scores. The absolute measured concentration of SPLI (SPLIabs) was divided by the TP concentration to obtain corrected SPLI (SPLIcorr) concentration.