Effect of ketanserin on pain perception in arterial hypertension

Hypertensive Hypoalgesia in a Complex Chronic Disease Population

Hypertension-related hypoalgesia, defined as lower pain sensitivity in individuals with high blood pressure, has yet to be examined in a large-scale study of complex care residents. Here, the Continuing Care Reporting System database, which contains health information on residents of Canadian complex chronic care facilities, was used for assessment. Hypertension was reported among 77,323 residents (55.5%, total N = 139,920). Propensity score matching, with a 1:1 ratio, was used to identify a control record without hypertension for each case. Multinomial logistic regression was used to quantify the effects of hypertension and sex on four-level ordinal pain variables, controlling for potential confounders. The matched dataset included n = 40,799 cases with hypertension and n = 40,799 without hypertension, with 57% female. Residents with hypertension had significantly lower odds of reporting pain (yes/no) (OR = 0.85, 95% CI 0.81–0.90, p < 0.001), including on measures of severe pain (OR = 0.69, 95% CI 0.63–0.76, p < 0.001). A significant interaction between hypertension and sex (OR = 1.17, 95% CI 1.03–1.32, p = 0.014) indicated that a significantly greater proportion of females without hypertension reported severe pain (8.71%). The results confirm the relationship between hypertension and reduced pain sensitivity on a population level.

Examination of the dose-response relationship between pain perception and blood pressure elevations induced by isometric exercise in men and women

The purpose of this study was to examine exercise-induced hypoalgesia (EIH) in men and women, and whether different magnitudes of BP elevations induced by isometric exercise systematically influenced pain perception. Twenty-five men and 25 women performed isometric exercise at 25% MVC for 1-min, 3-min, and 5-min while BP and pain perception were assessed. Results indicated that BP was significantly elevated (p<0.05) by isometric exercise in a dose-response manner. Pain thresholds were found to be elevated while pain ratings were lower (p<0.05) immediately following isometric exercise but not in a dose-response manner. It was concluded that isometric exercise produced EIH in men and women, and there was not a dose-response relationship between BP and EIH.

Assessment of opiate modulation of pain and nociceptive responding in young adults with a parental history of hypertension

This double blind, placebo-controlled study examined the effects of an opiate antagonist, naltrexone, on nociceptive flexion reflex (NFR) thresholds and subjective pain in individuals with and without a parental history of hypertension. Using a repeated measures design, NFR threshold was repeatedly assessed on two testing days after administration of either placebo or naltrexone. Immediately after NFR threshold was determined, participants rated the level of pain experienced during the preceding NFR assessment, and at the end of each session participants' electrocutaneous pain threshold was assessed. Two primary findings were obtained. First, individuals with a parental history of hypertension exhibited attenuated pain sensitivity. Second, endogenous opioid blockade was associated with increased pain ratings in women but with increased pain threshold in men. In sum, the present study did not support a direct involvement of the endogenous opioid system in the attenuated pain sensitivity observed in individuals at increased risk for hypertension.

Changes in pain perception during treatment with angiotensin converting enzyme-inhibitors and angiotensin II type 1 receptor blockade

OBJECTIVES

Besides the well-known role of the angiotensin system in blood pressure control, an interaction of angiotensin and pain perception has been suggested. This study sought to investigate whether an angiotensin converting enzyme inhibitor, which facilitates bradykinins, algesic peptides, and/or an AT1 receptor antagonist may modify hypertension-related hypoalgesia in humans. The study was approved by the ethical committee of our Department.

METHODS

A total of 22 hypertensive patients were submitted to dental pulp stimulation to obtain the dental pain threshold and tolerance, and to 24 h blood pressure monitoring together with a control group of 55 normotensives. Then the hypertensives were randomized to enalapril or losartan treatment and were re-evaluated (dental pain perception and ambulatory monitoring) after 8 weeks of the first treatment and after an additional 8 weeks of the second treatment.

RESULTS

Untreated hypertensives showed a reduced perception to painful stimuli when compared with normotensives. A significant reduction of both pain threshold and tolerance was observed during the anti-hypertensive treatments (Friedman test: P = 0.007 and P = 0.006, respectively). Pain sensitivity was similar during the two treatments and it did not differ from pain sensitivity values of normotensive controls. ANCOVAs were computed to evaluate the relationship between anti-hypertensive agents and pain sensitivity, after controlling for blood pressure. A 24 h mean pressure served as covariate, removing any effect of blood pressure; a significant difference was observed entering both pain threshold and tolerance as dependent variables (F = 5.28, P = 0.0076; F = 8.16, P = 0.0007, respectively).

CONCLUSIONS

Both the angiotensin converting enzyme inhibitor enalapril and the AT1 receptor blocking agent losartan acted similarly on pain threshold and tolerance, pain sensitivity being increased during the two anti-hypertensive treatments. The blood pressure reduction during drug assumption could not account for the pain sensitivity changes observed. The latter may be due to a specific pharmacodynamic mechanism mediated through angiotensin II AT1 receptors.