Jeffrey J. Sherman

Endogenous opioids inhibit ambulatory blood pressure during naturally occurring stress.

Objective Laboratory experiments suggest that endogenous opioids inhibit blood pressure responses during psychological stress. Moreover, there seem to be considerable individual differences in the efficacy of opioid blood pressure inhibition, and these differences may be involved in the expression of risk for cardiovascular disease. To further evaluate the possible role of opioid mechanisms in cardiovascular control, the present study sought to document the effects of the long-lasting oral opioid antagonist naltrexone (ReVia, DuPont, Wilmington, DE) on ambulatory blood pressure responses during naturally occurring stress. Method Thirty male volunteers participated in a laboratory stress study using naltrexone followed by ambulatory blood pressure monitoring during the subsequent 24-hour period. Within-subject analyses were performed on ambulatory blood pressures under placebo and naltrexone conditions. Results Laboratory results indicate no significant group effects of naltrexone on blood pressure levels or reactivity. Ambulatory results indicate that during periods of low self-reported stress, no effect of opioid blockade was apparent. In contrast, during periods of high stress, opioid blockade increased ambulatory blood pressure. Conclusions These findings suggest that naltrexone-sensitive opioid mechanisms inhibit ambulatory blood pressure responses during naturally occurring stress.

The Variable Responding Scale for Detection of Random Responding on the Multidimensional Pain Inventory

This study developed a scale for detecting random responding on the Multidimensional Pain Inventory (MPI). Ninety-five undergraduates (derivation sample) completed the MPI randomly, as did 2 cross-validation samples, 34 chronic pain patients (pain) and 115 health care professionals (health care). Up to 71% of random profiles appeared valid. For comparison in validity scale development, a clinical MPI sample (N = 507) was split into derivation and cross-validation samples. Given that responses to similar items should be consistent in nonrandom protocols, 8 pairs of highly intercorrelated items were selected. Absolute differences between pairs were summed into a variable responding (VR) scale; scores were contrasted across clinical and random groups. On the basis of derivation sample results, VR scale cut scores (from 12 to 17) were tested and found to discriminate accurately (p <.001) between the cross-validation clinical and the healthcare and pain random responding samples. The potential clinical utility of the VR scale to identify random MPI protocols is supported.

Psychological coping with acute pain: An examination of the role of endogenous opioid mechanisms

This study examined the relationship among endogenous opioids, Monitoring and Blunting coping styles, and acute pain responses. Fifty-eight male subjects underwent a 1-min pressure pain stimulus during two laboratory sessions. Subjects experienced this pain stimulus once under endogenous opioid blockade with naltrexone and once in a placebo condition. Blunting was found to be negatively correlated with pain ratings, but this relationship was significantly more prominent under opioid blockade. Results for coping behaviors subjects used to manage the experimental pain were generally consistent with the Blunting results, indicating that cognitive coping was related more strongly to decreased pain ratings and cardiovascular stress responsiveness under opioid blockade. Overall, the beneficial effects of Blunting and cognitive coping on pain responses did not depend upon endogenous opioids and, in fact, became stronger when opioid receptors were blocked. The relationship between endogenous opioids and coping appears to be dependent upon situational and stimulus characteristics.

The effects of age, gender, and family history on blood pressure of normotensive college students

Offspring with a parental history of hypertension are, by some estimates, four times more likely to develop the disease (Corvol et al., 1992). While some studies suggest that an increased risk is observable in eight year old children, others suggest that the increased risk does not become apparent until age 20. This study examined this discrepancy by screening resting blood pressures from 403 young adults. After adjusting for body mass, a significant family history × age × gender interaction (p<.01) suggests that the effect of family history on systolic blood pressure varies by age and gender. The influence of positive family history becomes apparent in males by age 20 and in females by age 22. This relationship may help provide a rationale for interpretation and reconciliation of disparate results in the literature, and clarify our understanding of the etiologic mechanisms responsible for development of essential hypertension.

Influence of a sympathomimetic amine on masticatory and trapezius pain/pressure thresholds and electromyographic levels

OBJECTIVESnThis study examined the influence of terbutaline, a beta-adrenergic sympathomimetic amine on pain/pressure thresholds in the index fingers and masseter and trapezius muscles and electromyographic activity in trapezii.nnnSTUDY DESIGNnIn a randomized and double-blind controlled trial, 20 asymptomatic female subjects were assigned to receive either an injection of terbutaline or sterile water before collection of pain/pressure thresholds and electromyographic levels. Repeated analysis of variance and paired t tests were calculated to test for baseline and postinjection differences between groups.nnnRESULTSnNo significant baseline or postinjection group differences in pain/pressure thresholds or electromyographic were detected.nnnCONCLUSIONSnbeta-adrenergic sympathomimetic stimulation does not influence pain/pressure thresholds or electromyographic activity in the masselet and trapezius muscles or pain/pressure thresholds in the index fingers. These results suggest that development of painful muscle conditions is not caused by elevations of sympathetic activity.