Relationship Between Pain Sensitivity, Cardiovascular Reactivity to Cold Pressor test and Indexes of Activity of the Adrenergic and Opioid System

Abstract

An association between increased blood pressure levels and hypoalgesia has been reported in the experimental animal and in man. The relation between pain perception and cardiovascular function is however still obscure. In order to gain some insight into this aspect, normotensive subjects with low and high tolerance to pain, as assessed by tooth pulp stimulation, were compared for blood pressure and heart rate during cold pressor test, 24 hr urinary catecholamines, supine and upright PRA and plasma β-endorphin levels.

No significant difference was observed between the two groups for casual blood pressure, heart rate and PRA. Compared to subjects with low tolerance to pain, those with high tolerance to pain were significantly older and had: 1) significantly higher levels of diastolic blood pressure and of β endorphin levels dwing cold pressor test; 2) significantly higher B-endorphin levels after cold pressor test; 3) a significantly higher excretion of noradrenaline (but not of adrenaline and dopamine).

Key Words:

• beta endorphins
• cardiovascular reactivity
• pain