DO ENDOGENOUS OPIOIDS MEDIATE THE RELATIONSHIP BETWEEN BLOOD-PRESSUREAND PAIN SENSITIVITY IN NORMOTENSIVES

Elevated resting blood pressure is associated with decreased pain sens itivity in both animals and humans. Recent evidence suggests that this relationship may be mediated by endogenous opioid peptides in hyperte nsives, but the precise mechanism has not been investigated in normote nsives. We examined the effect of opioid receptor blockade with naloxo ne on the relationship between resting blood pressure and pain sensiti vity in normotensive humans. Sixteen young adults were given cold pres ser and handgrip challenges after treatment with either naloxone or sa line in a placebo-controlled, within-subject design. Multiple regressi on procedures indicated that resting systolic blood pressure was a sig nificant predictor of cold pain ratings even after the effects of nalo xone were statistically controlled. The interaction between systolic b lood pressure and opioid blockade was non-significant. These data sugg est that the relationship between resting blood pressure and pain sens itivity in normotensive humans is mediated, at least in part, by non-o pioid mechanisms.