Assessing supraspinal modulation of pain perception in individuals at risk for hypertension.

In this study we tested the hypothesis that hypoalgesia in individuals at risk for hypertension is related to enhanced activation of supraspinal pain modulation systems. Supraspinal inhibition of pain signals was assessed using a diffuse noxious inhibitory control paradigm, in which a noxious conditioning stimulus was used to suppress pain in response to a noxious test stimulus applied to a remote area of the body. Specifically, the nociceptive flexion reflex (NFR) was assessed in 113 healthy young adults before, during, and after exposure to forearm tourniquet ischemia. Consistent with previous evidence of hypoalgesia in individuals at risk for hypertension, offspring of hypertensive individuals exhibited significantly higher NFR thresholds than offspring of normotensive persons. Although NFR activity was significantly decreased in all participants during concomitant application of forearm ischemia, the degree of attenuation of NFR activity was not significantly different as a function of risk for hypertension.