Nociceptive flexion reflex and pain rating responses during endogenous opiate blockade with naltrexone in healthy young adults

The effect of opioid blockade on nociceptive flexion reflex (NFR) activity and subjective pain ratings was examined in 151 healthy young men and women. Using a within-subjects design, NFR threshold was assessed on 2 days after administration of either placebo or a 50mg dose of naltrexone. Electrocutaneous pain threshold and tolerance levels were measured after NFR threshold assessment on each day. Results indicated that administration of naltrexone was consistently associated with hypoalgesic responding. Specifically, participants exhibited lower levels of NFR activity and reported lower pain ratings for electrocutaneous stimulation delivered at pain threshold and tolerance levels following administration of naltrexone as compared to placebo. These findings indicate that opiate blockade using the current standard dose may elicit hypoalgesia. A potential moderating effect of dose of opiate-blockade medication and level of endogenous opioid activation should be carefully examined in future research.     

Parental history of hypertension and enhanced cardiovascular reactivity are associated with decreased pain ratings

Ischemic pain was examined in adult males with and without a parental history of hypertension. Blood pressure and heart rate were recorded during baseline, cold pressor, and ischemia. Repeated pain ratings were obtained during cold pressor and ischemia, and the McGill Pain Questionnaire was completed after each stressor. A median split was used to identify high and low mean arterial pressure and heart rate reactors to cold pressor. Parental history of hypertension, high heart rate reactivity, and high mean arterial pressure reactivity were each associated with significantly lower ischemic pain ratings on the McGill Pain Questionnaire, suggesting that risk for hypertension is associated with hypoalgesia in normotensives.     

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.     

Pain perception and cardiovascular responses in men with positive parental history for hypertension

Evidence suggests a reduced pain sensitivity in hypertensive individuals. This study sought to extend this work to normotensive individuals with hypertensive parents. Men with a positive (PH+) or negative (PH?) parental history for hypertension rated their pain every 15 s during a 90-s hand cold pressor test and for 90 s after the cold pressor test. Systolic (SBP) and diastolic (DBP) blood pressures and heart rate were measured throughout. After the cold pressor test, the men recalled their pain using the McGill Pain Questionnaire. PH+ men showed greater SBP and DBP responses to the cold pressor test. Although pain ratings during the cold pressor test did not differ between groups, posttest reported pain receded faster in the PH+ than in the PH? men. The PH+ men also reported less total pain on the McGill. These findings support the hypothesis that risk for hypertension may be associated with attenuated pain responses to nociceptive stimuli.     

Decreased pain perception and risk for hypertension: considering a common physiological mechanism.

For almost two decades, researchers have demonstrated that hypertension is reliably associated with decreased perception of pain. More recently, a growing body of evidence has begun to suggest that hypoalgesia is not a consequence of high blood pressure, as the phenomenon precedes the onset of hypertension in individuals at risk for the disorder. This article provides a review of empirical evidence of decreased pain perception in normotensive persons with a family history of hypertension, elevated resting blood pressure, or exaggerated cardiovascular reactivity to stress. Based on the existing evidence, hypoalgesia is argued to be a correlate of dysregulation of central nervous system structures involved in both pain control and cardiovascular regulation in individuals who are genetically predisposed to develop high blood pressure. As such, hypoalgesia may serve as a valuable method of identifying individuals at greatest risk for hypertension.     

Cognitive function and cardiovascular responsivity in subjects with a parental history of hypertension

College-age subjects with and without a parental history of hypertension completed a battery of tests of cognitive function on two separate occasions. Pulse rate and blood pressure were measured during performance of each task. In one session, subjects were told that their performance was being evaluated and videotaped from behind an observation mirror (Evaluation Condition). In the other session, subjects were told that their performance was not being observed (Nonevaluation Condition). Regardless of Evaluation Condition, Parental History subjects exhibited slower search of short-term memory than Non-Family History subjects during the first but not the second testing session. Parental History subjects displayed greater elevations in pulse rate than Nonparental History subjects during task performance. The results were interpreted as providing evidence that pathophysiological mechanisms associated with essential hypertension are not the only viable explanations of lower levels of cognitive performance exhibited by hypertensive subjects.This research was supported in part by NIH Grant AG-03055 from the National Institute on Aging.     

Simple reaction time as a function of the phase of the cardiac cycle in young adults at risk for hypertension

Modulation of simple reaction time over the cardiac cycle, which is likely to be mediated by activation of arterial baroreceptors, may be moderated by individual difference factors that affect baroreceptor activation, such as risk for hypertension. This study examined arterial baroreceptor effects on simple reaction times by presenting vibrotactile stimuli at six intervals after the R-wave of the electrocardiogram (0, 150, 300, 450, 600, and 750 ms) in 113 young men and women whose resting blood pressure and parental history of hypertension were ascertained. Reaction times were slower early in the cardiac cycle compared to later. However, these cycle time effects were not moderated by sex, resting blood pressure, or parental history of hypertension. In conclusion, cardiac-related cortical interference was not moderated by risk for hypertension.     

Effects of opioid blockade on nociceptive flexion reflex thresholds and nociceptive responding in hypertensive and normotensive individuals

Hypertension and risk for hypertension have been associated with reduced pain sensitivity. It has been hypothesised that endogenous opioids contribute to this hypertensive hypoalgesia. The nociceptive flexion reflex can be used as a tool to investigate modulation of nociceptive transmission at spinal level. The current study employed a double-blind placebo-controlled design to compare the effects of naltrexone, an opioid antagonist, and placebo on nociceptive flexion reflex thresholds and nociceptive responding in unmedicated patients with essential hypertension and normotensive individuals. Neither nociceptive flexion reflex thresholds nor nociceptive responding differed between hypertensives and normotensives during placebo or naltrexone. These data provide no support for the hypothesis that essential hypertension is characterised by higher levels of endogenous opioids in the central nervous system and reveal no association between blood pressure status and nociceptive flexion reflex responses.     

Blood pressure, gender, and parental hypertension are factors in baseline and poststress pain sensitivity in normotensive adults

We studied 38 men and 36 women to learn whether a brief speech stressor reduced normotensive humans thermal pain sensitivity, whether baseline and poststress pain threshold and tolerance varied with blood pressure (BP) and hemodynamic measures, and whether these relations differed by gender and parental hypertension (PH). PH-women with low resting BPs had lower baseline pain tolerance than did all other groups (ps < .05), and this group alone exhibited stress-induced analgesia (ps = .008). In women, pre- and poststress pain tolerance varied directly with rest and stress BP (ps < .05). In men, BP and pain measures were not related, but high cardiac index during stress was associated with low baseline pain tolerance (p < .01). The present findings support the hypothesis that pain sensitivity and cardiac stress response share a common mechanism, but they yield little support for the hypothesis that analgesic responses to acute stress contribute to hypertension etiology via an instrumental learning process. We are grateful to Robin Campbell for her technical assistance and to Dr. Alan L. Hinderliter for his assistance in screening volunteers for participation in this study. This research was supported by Grant R01-HL3t533 from the National Health, Lung, and Blood Institute, Bethesda, MD     

Effects of parental history of hypertension and urbanization on blood pressure in zimbabweans

The increasing prevalence of essential hypertension is a growing public health concern for Zimbabwe and other African countries. Two important risk factors for hypertension are urbanization and parental history of hypertension. The relations among parental history of hypertension, urbanization, and blood pressures (BPs) are poorly understood. The objective of this study is to clarify these relations in a population of urbanized. African, young adults. The relation between parental history of hypertension and urbanization on resting BPs and BP responses to a menial arithmetic stressor was examined in a group of normotensive, Black medical students with (n = 36) and without (n = 34) a parental history of high BP.and with (n = 49) and without (n = 19) a parental history of urbanization. Results indicate that those with a positive parental history of high BP had higher resting BPs and greater systolic blood pressure (SBP) increases in response to laboratory stress, when compared to their negative parental history counterparts. Further, those with parents residing in urban areas had higher resting SBPs than those with parents residing in rural areas. However, no reactivity differences were apparent between the urban and rural parent groups. These data suggest that although parental history for hypertension influences both resting and reactivity BPs, parental history of urbanization may influence only resting BP. This study was supported by NIH/Fogarty International Center Grants 5T37TW3041-02, N1H-HL35195. and NIH-HL32738.     

Assessing parental history of hypertension: Father (and mother) knows best!

In hypertensive risk studies, offspring reports are often used to establish parental history of hypertension. This method is simple and less costly than contacting parents and has been reported to be ≥84% accurate when compared with parental confirmation. The present study examined two components that contribute to overall accuracy: sensitivity (correct identification of high blood pressure) and specificity (correct identification of normal blood pressure). Undergraduate volunteers (282 women, 211 men) provided parental blood pressure information, and then blood pressure history questionnaires were mailed to their biological parents. Comparison of offspring and parent reports revealed a combination of high specificity (92.9%) and low sensitivity (68.2%), suggesting that offspring reports may be misleading when attempting to identify hypertensive parents.     

Association of waist and hip circumferences with the presence of hypertension and pre-hypertension in young South African adults

BackgroundObesity is one of the most important risk factors for cardiovascular diseases (CVDs) including hypertension (HT) which is itself a risk factor for CVDs. Recent studies suggest that waist circumference (WC) may be more sensitive than Body Mass Index (BMI) in determining individual risk scores for CVDs.ObjectivesThe current study aimed at investigating the influence of various anthropometric variables on blood pressure status in a group of students from Walter Sisulu University.MethodsInformed consent was obtained from 216 male and female students from Walter Sisulu University with a mean age of 22.1±0.2 years. Anthropometric measurements were performed for each participant. Blood pressure was measured in triplicates after 10 minutes of rest and the average computed.ResultsJust over 46% of the subjects were diagnosed with hypertension (HT) and pre-HT. The gender specific prevalence of HT/pre-HT was higher in the male (76.7%) compared to the female (30.5%) group. Waist circumference (WC) and total body fat (TBF) correlated significantly with blood pressure and HT/pre-HT in females but not males. ROC analysis showed that with the exception of waist-to-hip (WHR), all other anthropometric measurements and ratios studied can be used to discriminate blood pressure in young adult females not males.ConclusionIncreased WC and HC were associated with HT and pre-HT in young adult females in the Walter Sisulu University.     

Attenuation of positive and negative affect in men and women at increased risk for hypertension: A function of endogenous barostimulation?

We hypothesized that activation of endogenous baroreflexes would be associated with reduced responsivity to affective stimuli and that this effect would be enhanced in individuals at risk for hypertension. Images from the International Affective Picture System were presented during systolic and diastolic phases of the cardiac cycle. Affective responsivity was measured using electromyographic activity, skin conductance, and ratings of arousal and valence. Compared to offspring of normotensives, individuals with a parental history of hypertension showed reduced responsivity to both positive and negative affective stimuli; however, responsivity did not differ as a function of cardiac cycle phase. Although these findings do not support a barostimulation mechanism of affective dampening, it is premature to discount the baroreflex inhibition hypothesis given the limited affective reactions elicited by visual stimuli presented in the laboratory.     

Vascular and baroreceptor abnormalities in young males with a family history of hypertension

Vascular and baroreceptor abnormalities in 44 young males, mean age 21 years, comprising of offspring with (FH⁺; n = 22) and without (FH⁻; n = 22) hypertensive parents, were investigated. Peak forearm blood flow (FBF), which was defined as the highest blood flow obtained following reactive hyperaemia, was assessed using strain gauge plethysmography following 5 min of ischemia. Cardiopulmonary baroreceptor sensitivity was assessed using lower body negative pressure for 5 min at −20 mmHg and was determined by calculating change of stroke volume and forearm vascular resistance (FVR) to lower body negative pressure. Carotid baroreceptor sensitivity was assessed using neck suction at −20, −40, −60, and −80 mmHg and was calculated by dividing RR interval by systolic blood pressure. Augmentation index, a measure of wave reflection, was assessed using applanation tonometry and was calculated as the ratio of augmented pressure and pulse pressure. Peak FBF of FH⁺ was 19% lower than the FH⁻ (p = 0.02). Also FH⁺ had 17% higher peak FVR compared to FH⁻ (p = 0.04). However, there were no significant differences between groups for cardiopulmonary, carotid baroreceptor sensitivity, and augmentation index. These results suggest that peripheral vascular dysfunction appears earlier than abnormal baroreceptor sensitivity in young males with a family history of hypertension.     

Cardiovascular reactivity and family history of hypertension: a meta-analysis

A regression-based meta-analysis examined the degree to which the effects of a family history of hypertension on cardiovascular reactivity are moderated by the magnitude of cardiovascular responses elicited in challenge/task conditions. Mean change scores for negative family history groups were regressed on mean change scores for positive family history groups. The slopes of separate regression lines obtained for systolic and diastolic blood pressure and heart rate were significantly less than 1.0 and the y-intercepts for these regression lines were significantly greater than zero. This pattern indicates that family history differences in cardiovascular reactivity to stress are greatest in situations that elicit the smallest baseline-stressor change scores in non-family-history groups.     

Effects of naltrexone on electrocutaneous pain in patients with hypertension compared to normotensive individuals

An opioid mechanism may help explain hypertensive hypoalgesia. A double-blind placebo-controlled design compared the effects of opioid blockade (naltrexone) and placebo on electrocutaneous pain threshold, pain tolerance, and retrospective McGill Pain Questionnaire ratings in 35 unmedicated patients with essential hypertension and 28 normotensive individuals. The hypertensives experienced less pain than normotensives during the assessment of their pain tolerance; however, this manifestation of hypertensive hypoalgesia was not moderated by naltrexone. These findings fail to support the hypothesis that essential hypertension is characterised by relative opioid insensitivity.     

Irreversible lung function deficits in young adults with a history of childhood asthma

BACKGROUND: Asthma, traditionally characterized as reversible airway obstruction, might lead to structural changes and permanent impairment. OBJECTIVE: We sought to study the frequency, severity, and reversibility of pulmonary deficits in adults with a history of moderate-to-severe childhood allergic asthma. METHODS: Subjects (n = 121) previously enrolled in a randomized trial of immunotherapy for childhood asthma were recalled. Eighty-four young adults (age, 17-30 years; 78% male) were reevaluated by means of spirometry. Subjects with a postbronchodilator FEV1, forced vital capacity, or FEV1/forced vital capacity ratio less than or equal to the 5th percentile or 2 or more indices less than or equal to the 10th percentile (National Health and Nutrition Examination Survey III normative data) were invited to undergo complete pulmonary function testing, physical examination, and chest radiography after 1 week of 1 mg/kg daily prednisone. RESULTS: Of 84 subjects reevaluated, 40 (48%) had one or more spirometric indices less than or equal to the 5th and 10th percentiles (P < .0001). Twenty-eight of the 40 subjects were reassessed after prednisone treatment, of whom 21 (75%) did not improve. Adult and childhood (age 5-12 years) spirometric results were positively correlated (r = 0.49-0.72, P < .001). Abnormal adult spirometric results were associated with a longer duration of asthma at enrollment in the original trial (4.6 vs 6 years, P=.02), increased childhood methacholine sensitivity (PC20, 0.11 vs 0.18 mg/mL; P = .01), and birth prematurity (adjusted odds ratio, 10.7; 95% CI, 1.4-84.5). Immunotherapy status was unrelated to adult lung function. CONCLUSIONS: Many adults with a history of moderate-to-severe allergic asthma in childhood have irreversible lung function deficits. Childhood spirometry, duration of asthma, methacholine sensitivity, and birth prematurity might identify such individuals at a young age.     

1例三高病史患者同种异体肝移植手术配合报道

报道1例三高病史患者同种异体肝移植患者的病例资料,归纳总结术中配合要点及护理关注点。特殊患者术前全面评估、术中细致配合是保障肝移植手术成功的保障。