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Schäfer M, Browne LP, Truong U, Bjornstad P, Tell S, Snell-Bergeon J, Baumgartner A, Hunter KS, Reusch JEB, Barker AJ, Nadeau KJ, Schauer IE. Bromocriptine Improves Central Aortic Stiffness in Adolescents With Type 1 Diabetes: Arterial Health Results From the BCQR-T1D Study. Hypertension 2023; 80:482-491. [PMID: 36472197 PMCID: PMC9852005 DOI: 10.1161/hypertensionaha.122.19547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 10/09/2022] [Indexed: 12/12/2022]
Abstract
BACKGROUND The presence of vascular dysfunction is a well-recognized feature in youth with type 1 diabetes (T1D), accentuating their lifetime risk of cardiovascular events. Therapeutic strategies to mitigate vascular dysfunction are a high clinical priority. In the bromocriptine quick release T1D study (BCQR-T1D), we tested the hypothesis that BCQR would improve vascular health in youth with T1D. METHODS BCQR-T1D was a placebo-controlled, random-order, double-blinded, cross-over study investigating the cardiovascular and metabolic impact of BCQR in T1D. Adolescents in the BCQR-T1D study were randomized 1:1 to phase-1: 4 weeks of BCQR or placebo after which blood pressure and central aortic stiffness measurements by pulse wave velocity, relative area change, and distensibility from phase-contrast magnetic resonance imaging were performed. Following a 4-week washout period, phase 2 was performed in identical fashion with the alternate treatment. RESULTS Thirty-four adolescents (mean age 15.9±2.6 years, hemoglobin A1c 8.6±1.1%, body mass index percentile 71.4±26.1, median T1D duration 5.8 years) with T1D were enrolled and had magnetic resonance imaging data available. Compared with placebo, BCQR therapy decreased systolic (∆=-5 mmHg [95% CI, -3 to -7]; P<0.001) and diastolic blood pressure (∆=-2 mmHg [95% CI, -4 to 0]; P=0.039). BCQR reduced ascending aortic pulse wave velocity (∆=-0.4 m/s; P=0.018) and increased relative area change (∆=-2.6%, P=0.083) and distensibility (∆=0.08%/mmHg; P=0.017). In the thoraco-abdominal aorta, BCQR decreased pulse wave velocity (∆=-0.2 m/s; P=0.007) and increased distensibility (∆=0.05 %/mmHg; P=0.013). CONCLUSIONS BCQR improved blood pressure and central and peripheral aortic stiffness and pressure hemodynamics in adolescents with T1D over 4 weeks versus placebo. BCQR may improve aortic stiffness in youth with T1D, supporting future longer-term studies.
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Affiliation(s)
- Michal Schäfer
- Division of Pediatric Cardiology, Department of Pediatrics, University of Colorado – School of Medicine, Aurora, CO
| | - Lorna P. Browne
- Department of Radiology, University of Colorado – School of Medicine, Aurora, CO
| | - Uyen Truong
- Department of Cardiology, Children’s Hospital of Richmond at Virginia Commonwealth University
| | - Petter Bjornstad
- Section of Pediatric Endocrinology, Department of Pediatrics, University of Colorado – School of Medicine, Aurora, CO
| | - Shoshana Tell
- Section of Pediatric Endocrinology, Department of Pediatrics, University of Colorado – School of Medicine, Aurora, CO
| | - Janet Snell-Bergeon
- Barbara Davis Center, Department of Medicine, University of Colorado – School of Medicine, Aurora, CO
| | - Amy Baumgartner
- Section of Pediatric Endocrinology, Department of Pediatrics, University of Colorado – School of Medicine, Aurora, CO
| | - Kendall S. Hunter
- Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus, CO
| | - Jane E. B. Reusch
- Section of Endocrinology, Rocky Mountain Regional VAMC, Aurora, CO
- Division of Endocrinology, Department of Medicine, University of Colorado – School of Medicine, Aurora, CO
- Center for Women’s Health Research, University of Colorado – School of Medicine, Aurora, CO
| | - Alex J. Barker
- Department of Radiology, University of Colorado – School of Medicine, Aurora, CO
- Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus, CO
| | - Kristen J. Nadeau
- Section of Pediatric Endocrinology, Department of Pediatrics, University of Colorado – School of Medicine, Aurora, CO
| | - Irene E. Schauer
- Section of Endocrinology, Rocky Mountain Regional VAMC, Aurora, CO
- Division of Endocrinology, Department of Medicine, University of Colorado – School of Medicine, Aurora, CO
- Center for Women’s Health Research, University of Colorado – School of Medicine, Aurora, CO
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Tell SS, Schafer M, Vigers T, Baumgartner AD, Lyon E, Gross S, Polsky S, Snell-Bergeon JK, Schauer IE, Nadeau KJ. Bromocriptine quick-release as adjunct therapy in youth and adults with type 1 diabetes: A randomized, placebo-controlled crossover study. Diabetes Obes Metab 2022; 24:2148-2158. [PMID: 35712800 PMCID: PMC10849845 DOI: 10.1111/dom.14800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 06/07/2022] [Accepted: 06/12/2022] [Indexed: 11/28/2022]
Abstract
AIM To evaluate the potential for glycaemic, renal and vascular benefits of bromocriptine quick release (BCQR) in adolescents and adults with type 1 diabetes. MATERIALS AND METHODS Forty adolescents and 40 adults with type 1 diabetes aged 12-60 years old were enrolled in a double-blind, placebo-controlled, random order crossover study of 4 weeks of treatment in the morning with BCQR (titrated weekly from 0.8 mg to 1.6 mg to 3.2 mg, minimum dose 1.6 mg). Study assessments after each phase included blood pressure (BP), lipids, peripheral arterial stiffness and autonomic function, mixed meal tolerance test, continuous glucose monitoring (CGM), creatinine, estimated glomerular filtration rate, estimated insulin sensitivity, insulin dose and indirect calorimetry. RESULTS Adolescents displayed baseline hyperglycaemia, insulin resistance, metabolic dysfunction and increased renal filtration compared with adults. In both age groups, continuous glucose monitoring measures, estimated insulin sensitivity and insulin dose did not differ with BCQR treatment. In adolescents, BCQR decreased systolic BP, diastolic BP and triangular index and increased serum creatinine. In adults, systolic BP, mean arterial pressure, systemic vascular resistance, and mixed meal tolerance test glucose and glucagon-like peptide 1 areas under the curve were lower, and the orthostatic drop in systolic BP was greater with BCQR. CONCLUSIONS Greater hyperglycaemia, insulin resistance, metabolic dysfunction and renal hyperfiltration in adolescents argues for increased attention during this high-risk age period. Although BCQR had little impact on glycaemia or insulin sensitivity, initial vascular and renal responses suggest potential benefits of BCQR in adolescents and adults with type 1 diabetes requiring further study.
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Affiliation(s)
- Shoshana S Tell
- Division of Pediatric Endocrinology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
- Barbara Davis Center for Childhood Diabetes, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Michal Schafer
- Division of Pediatric Cardiology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Timothy Vigers
- Barbara Davis Center for Childhood Diabetes, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Amy D Baumgartner
- Division of Pediatric Endocrinology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Ellen Lyon
- Division of Endocrinology and Metabolism, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Susan Gross
- Division of Pediatric Endocrinology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Sarit Polsky
- Barbara Davis Center for Childhood Diabetes, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Janet K Snell-Bergeon
- Barbara Davis Center for Childhood Diabetes, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Irene E Schauer
- Division of Endocrinology and Metabolism, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
- Endocrinology Section, Rocky Mountain Regional VA Medical Center, Aurora, Colorado, USA
| | - Kristen J Nadeau
- Division of Pediatric Endocrinology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
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Han Y, Du J, Wang J, Liu B, Yan YL, Deng SB, Zou Y, Jing XD, Du JL, Liu YJ, She Q. Cold Pressor Test in Primary Hypertension: A Cross-Sectional Study. Front Cardiovasc Med 2022; 9:860322. [PMID: 35548443 PMCID: PMC9081644 DOI: 10.3389/fcvm.2022.860322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Accepted: 03/22/2022] [Indexed: 11/13/2022] Open
Abstract
Objectives To investigate the characteristics of patients with primary hypertension who had positive responses to the cold pressor test (CPT). Methods This cross-sectional study was conducted between November 2018 to November 2019, and the CPT was performed in patients with primary hypertension in 48 hospitals. The demographic characteristics and complications were collected through a questionnaire and physical examinations. A 12-month follow-up was conducted to identify the occurrence of the following events: a) all-cause mortality; b) myocardial infarction; c) stroke; d) hospitalized for heart failure. Results The CPT was positive in 30.7% of the patients. Compared with the negative CPT group, the positive CPT group was associated with a lower rate of blood pressure control, and was more likely to have a high salt diet, diabetes, hyperuricemia, left ventricular wall thickening, carotid plaques, coronary heart disease and heart failure. A high-salt diet (OR = 1.228, 95%CI: 1.037–1.456) was found to be correlated with the positive result of CPT. Among patients in the positive CPT group, those using diuretics had a significantly higher rate of blood pressure control than those not using diuretics (54.6 vs.42.6%, x2 = 6.756, P = 0.009). After a 12-month follow-up, the incidence of heart failure in the positive CPT group was significantly higher than that in the negative CPT group (7.35 vs.5.01%, x2 = 3.945, P = 0.047). Conclusions Patients with positive responses to the CPT had lower rates of BP control and a high risk of heart failure, which may be related to their preference for a high-salt diet. The use of diuretics helps to better control blood pressure in those patients.
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Takeda R, Stickford ASL, Best SA, Yoo JK, Liu YL, Fu Q. Effects of salt intake on sympathetic neural and pressor responses to cold pressor test in premenopausal women with a history of normal pregnancy. Am J Physiol Regul Integr Comp Physiol 2021; 320:R307-R316. [PMID: 33438516 DOI: 10.1152/ajpregu.00297.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Excessive salt intake is considered a risk factor for the development of hypertension. Additionally, aberrant neurocirculatory responses to a cold stimulus are associated with an increased risk of hypertension. This study aimed to determine whether salt loading versus salt reduction would impact hemodynamic and sympathetic neural responses during the cold pressor test (CPT) in premenopausal women with a history of normal pregnancy. Nine healthy premenopausal women [42 ± 3 (SD) yr] were given a standardized isocaloric high-salt (HS; 250 mEq sodium/day) or low-salt (LS; 50 mEq sodium/day) diet for 1-wk each (∼2 mo apart with the order randomized), while water intake was ad libitum. Laboratory testing was performed following each HS and LS period in the mid-luteal phase of the menstrual cycle. Subjects were in the supine position and beat-by-beat blood pressure (BP), heart rate (HR), and muscle sympathetic nerve activity (MSNA) were continuously measured during 1-min baseline followed by 2-min CPT, and 3-min recovery. BP and HR increased during the CPT (both P < 0.001); the responses were similar between HS and LS. MSNA increased during the CPT, but the increment (Δ) was greater during HS than LS (29 ± 6 vs. 15 ± 4 bursts/min; P < 0.001). The transduction of MSNA for vasoconstriction during the CPT was lower in HS (P < 0.05). Thus, salt loading augments sympathetic neural reactivity to the cold stimulus with similar pressor responses compared with salt reduction, which may be attributed to the blunted neurovascular transduction-a compensatory mechanism for hemodynamic homeostasis in premenopausal women with a history of normal pregnancy.
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Affiliation(s)
- Ryosuke Takeda
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas.,Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Abigail S L Stickford
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas.,Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Stuart A Best
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas.,Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Jeung-Ki Yoo
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas.,Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Yu-Lun Liu
- Department of Population and Data Sciences, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Qi Fu
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas.,Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas
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Lewis AH, Porcelli AJ, Delgado MR. The effects of acute stress exposure on striatal activity during Pavlovian conditioning with monetary gains and losses. Front Behav Neurosci 2014; 8:179. [PMID: 24904331 PMCID: PMC4033231 DOI: 10.3389/fnbeh.2014.00179] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Accepted: 04/28/2014] [Indexed: 01/08/2023] Open
Abstract
Pavlovian conditioning involves the association of an inherently neutral stimulus with an appetitive or aversive outcome, such that the neutral stimulus itself acquires reinforcing properties. Across species, this type of learning has been shown to involve subcortical brain regions such as the striatum and the amygdala. It is less clear, however, how the neural circuitry involved in the acquisition of Pavlovian contingencies in humans, particularly in the striatum, is affected by acute stress. In the current study, we investigate the effect of acute stress exposure on Pavlovian conditioning using monetary reinforcers. Participants underwent a partial reinforcement conditioning procedure in which neutral stimuli were paired with high and low magnitude monetary gains and losses. A between-subjects design was used, such that half of the participants were exposed to cold stress while the remaining participants were exposed to a no stress control procedure. Cortisol measurements and subjective ratings were used as measures of stress. We observed an interaction between stress, valence, and magnitude in the ventral striatum, with the peak in the putamen. More specifically, the stress group exhibited an increased sensitivity to magnitude in the gain domain. This effect was driven by those participants who experienced a larger increase in circulating cortisol levels in response to the stress manipulation. Taken together, these results suggest that acute stress can lead to individual differences in circulating cortisol levels which influence the striatum during Pavlovian conditioning with monetary reinforcers.
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Affiliation(s)
- Andrea H Lewis
- Department of Psychology, Rutgers University Newark, NJ, USA
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Vélez JM, Chamorro GA, Calzada CC, Zuñiga CA, Vélez JJ, Ocharán E. A study of prevention and regression of cardiac hypertrophy with a prolactin inhibitor in a biological model of ventricular hypertrophy caused by aorto caval fistulae in rat. Cardiovasc Pathol 2013; 22:357-67. [PMID: 23478013 DOI: 10.1016/j.carpath.2013.01.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 01/11/2013] [Accepted: 01/11/2013] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND The possibility of decreasing or reverting left ventricular hypertrophy and, therefore, cardiac hypertrophy (CH) is an important medical issue. The aim of the present study was to evaluate these two possibilities with a 3-week daily dose of captopril, losartan, or bromocriptine in a preventive or corrective model. METHODS After aorto caval fistulae (ACF) surgery on adult male Wistar rats to induce CH, animals were assigned to the preventive protocol (drug treatment began immediately after surgery) or corrective protocol (hypertrophy was allowed to develop before drug treatment). After treatments, isoproterenol was administered to half of the animals to further induce CH. The groups included the passive control, the sham-operated animals, those with ACF surgery but without drug treatment, and the 3-week treatments with captopril, losartan, or the low or high dose of bromocriptine. RESULTS Three treatments, with captopril, losartan, or the high dose of bromocriptine, significantly impeded/reverted an increase in CH-related parameters in the preventive/corrective model compared to the surgically treated group without drug treatment. The same effect was found after isoproterenol administration. The present results show an avoidance/reversion of CH with these three treatments. Better results were found with the angiotensin converting enzyme inhibitor (captopril) than with the prolactin inhibitor (bromocriptine). CONCLUSIONS Treatments with captopril, losartan, and the high dose of bromocriptine were effective in preventing/reversing the manifestation of CH in the preventive/corrective rat models. Further studies are needed to identify the initial mediator, the key component, and the molecular events involved in the pathogenesis of CH.
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Affiliation(s)
- Juan M Vélez
- Intracellular Signaling Laboratory, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, México
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Abstract
A placebo-controlled prospective safety study of quick-release bromocriptine in patients with type 2 diabetes has shown a 40% reduction in cardiovascular events. Possible explanations for this decrease are that through re-establishing diurnal variation a decrease in insulin resistance and its associated risk factors occurs. In addition, a decrease in the activity of the sympathetic nervous and renin-angiotensin systems and re-establishment of diurnal variations in the pituitary-adrenal axis may play a role. However, the most probable explanation is that because of the lowering of insulin resistance there are decreases in hepatic glucose production and an increased uptake of glucose leading to decreased levels of postprandial glucose, free fatty acids and triglycerides, which cause decreases in inflammation, oxidative stress and accumulation of atheroma.
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Affiliation(s)
- D S H Bell
- University of Alabama-Birmingham, Southside Endocrinology, Birmingham, AL 35205, USA.
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Wacker J, Stemmler G. Agentic extraversion modulates the cardiovascular effects of the dopamine D2 agonist bromocriptine. Psychophysiology 2006; 43:372-81. [PMID: 16916433 DOI: 10.1111/j.1469-8986.2006.00417.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A recent psychobiological theory postulates a dopaminergic basis for the agency facet of extraversion, leading to the prediction that this personality trait modulates the psychophysiological effects of dopaminergic drugs. A single dose of the dopamine D2 receptor agonist bromocriptine reduces blood pressure in healthy volunteers. However, it is currently unknown whether this hypotensive effect of bromocriptine is modulated by agentic extraversion. Therefore, we measured resting cardiovascular activation in groups of healthy male volunteers either high or low in agentic extraversion, either under bromocriptine (1.25 mg) or placebo. Focusing the analyses on activation components derived from 18 cardiovascular variables, we found that bromocriptine reduces alpha-adrenergic activation in the sample as a whole, whereas the effects on beta-adrenergic and cholinergic activation are modulated by agentic extraversion.
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Affiliation(s)
- Jan Wacker
- Faculty of Psychology, Philipps-Universität Marburg, Marburg, Germany.
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Takahashi T, Murata T, Hamada T, Omori M, Kosaka H, Kikuchi M, Yoshida H, Wada Y. Changes in EEG and autonomic nervous activity during meditation and their association with personality traits. Int J Psychophysiol 2005; 55:199-207. [PMID: 15649551 DOI: 10.1016/j.ijpsycho.2004.07.004] [Citation(s) in RCA: 195] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2003] [Revised: 07/17/2004] [Accepted: 07/20/2004] [Indexed: 10/26/2022]
Abstract
Meditation is the attainment of a restful yet fully alert physical and mental state practiced by many as a self-regulatory approach to emotion management, but the psychophysiological properties and personality traits that characterize this meditative state have not been adequately studied. We quantitatively analyzed changes in psychophysiological parameters during Zen meditation in 20 normal adults, and evaluated the results in association with personality traits assessed by Cloninger's Temperament and Character Inventory (TCI). During meditation, increases were observed in fast theta power and slow alpha power on EEG predominantly in the frontal area, whereas an increase in the normalized unit of high-frequency (nuHF) power (as a parasympathetic index) and decreases in the normalized unit of low-frequency (nuLF) power and LF/HF (as sympathetic indices) were observed through analyses of heart rate variability. We analyzed the possible correlations among these changes in terms of the percent change during meditation using the control condition as the baseline. The percent change in slow alpha EEG power in the frontal area, reflecting enhanced internalized attention, was negatively correlated with that in nuLF as well as in LF/HF and was positively correlated with the novelty seeking score (which has been suggested to be associated with dopaminergic activity). The percent change in fast theta power in the frontal area, reflecting enhanced mindfulness, was positively correlated with that in nuHF and also with the harm avoidance score (which has been suggested to be associated with serotonergic activity). These results suggest that internalized attention and mindfulness as two major core factors of behaviors of mind during meditation are characterized by different combinations of psychophysiological properties and personality traits.
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Affiliation(s)
- Tetsuya Takahashi
- Department of Neuropsychiatry, Faculty of Medical Sciences, University of Fukui, Matsuoka-cho, Fukui 910-1193, Japan
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Kan SF, Kau MM, Low-Tone Ho L, Wang PS. Inhibitory effects of bromocriptine on corticosterone secretion in male rats. Eur J Pharmacol 2003; 468:141-9. [PMID: 12742521 DOI: 10.1016/s0014-2999(03)01663-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Bromocriptine, a dopamine D2 receptor agonist, is widely used for treating prolactinoma, Parkinson's disease and galactorrhea. However, the influence of bromocriptine on the endocrine system, especially adrenal function, is not clear. The present study was aimed to investigate the effects of bromocriptine on corticosterone production in rats. Male rats were treated or not treated by bromocriptine (5 mg/kg, s.c.) twice per day for 2 days before decapitation. The adrenal zona fasciculata-reticularis cells were prepared and incubated with adrenocorticotropic hormone (ACTH), forskolin (an adenylyl cyclase activator), 8-bromo-adenosine 3':5' cyclic monophosphate (8-Br-cAMP, a membrane-permeable analogue of cAMP), and steroidogenic precursors including 25-OH-cholesterol and pregnenolone. The concentrations of prolactin, corticosterone and pregnenolone in the plasma and/or medium were measured by radioimmunoassay (RIA). The protein expression of cytochrome P450 side-chain cleavage (P450scc) enzyme and steroidogenic acute regulatory protein (StAR) was analyzed by Western blotting. Administration of bromocriptine in vivo resulted in a decrease in the levels of plasma prolactin and corticosterone. Basal--and ACTH--as well as forskolin-stimulated corticosterone secretion by zona fasciculata-reticularis cells was also lower in bromocriptine-treated rats than in control animals. The decreased production of corticosterone in zona fasciculata-reticularis cells could be reversed by administration of 8-Br-cAMP. The corticosterone and pregnenolone release induced by 25-OH-cholesterol in zona fasciculata-reticularis cells was reduced by administration of bromocriptine. The protein expression of both StAR protein and P450scc in zona fasciculata-reticularis cells was inhibited in the bromocriptine-treated group. Administration of bromocriptine in vitro reduced the release of corticosterone stimulated by ACTH and forskolin in rat zona fasciculata-reticularis cells. These results suggested that bromocriptine caused adrenal dysfunction through inhibition of ACTH action and of the activity of adenylyl cyclase, and impaired the early steps of corticosterone biosynthesis.
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Affiliation(s)
- Shu Fen Kan
- Department of Physiology, School of Medicine, National Yang-Ming University, Taipei, Taiwan, ROC
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Fu Q, Levine BD, Pawelczyk JA, Ertl AC, Diedrich A, Cox JF, Zuckerman JH, Ray CA, Smith ML, Iwase S, Saito M, Sugiyama Y, Mano T, Zhang R, Iwasaki K, Lane LD, Buckey JC, Cooke WH, Robertson RM, Baisch FJ, Blomqvist CG, Eckberg DL, Robertson D, Biaggioni I. Cardiovascular and sympathetic neural responses to handgrip and cold pressor stimuli in humans before, during and after spaceflight. J Physiol 2002; 544:653-64. [PMID: 12381834 PMCID: PMC2290607 DOI: 10.1113/jphysiol.2002.025098] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Astronauts returning to Earth have reduced orthostatic tolerance and exercise capacity. Alterations in autonomic nervous system and neuromuscular function after spaceflight might contribute to this problem. In this study, we tested the hypothesis that exposure to microgravity impairs autonomic neural control of sympathetic outflow in response to peripheral afferent stimulation produced by handgrip and a cold pressor test in humans. We studied five astronauts approximately 72 and 23 days before, and on landing day after the 16 day Neurolab (STS-90) space shuttle mission, and four of the astronauts during flight (day 12 or 13). Heart rate, arterial pressure and peroneal muscle sympathetic nerve activity (MSNA) were recorded before and during static handgrip sustained to fatigue at 40 % of maximum voluntary contraction, followed by 2 min of circulatory arrest pre-, in- and post-flight. The cold pressor test was applied only before (five astronauts) and during flight (day 12 or 13, four astronauts). Mean (+/- S.E.M.) baseline heart rates and arterial pressures were similar among pre-, in- and post-flight measurements. At the same relative fatiguing force, the peak systolic pressure and mean arterial pressure during static handgrip were not different before, during and after spaceflight. The peak diastolic pressure tended to be higher post- than pre-flight (112 +/- 6 vs. 99 +/- 5 mmHg, P = 0.088). Contraction-induced rises in heart rate were similar pre-, in- and post-flight. MSNA was higher post-flight in all subjects before static handgrip (26 +/- 4 post- vs. 15 +/- 4 bursts min(-1) pre-flight, P = 0.017). Contraction-evoked peak MSNA responses were not different before, during, and after spaceflight (41 +/- 4, 38 +/- 5 and 46 +/- 6 bursts min(-1), all P > 0.05). MSNA during post-handgrip circulatory arrest was higher post- than pre- or in-flight (41 +/- 1 vs. 33 +/- 3 and 30 +/- 5 bursts min(-1), P = 0.038 and 0.036). Similarly, responses of MSNA and blood pressure to the cold pressor test were well maintained in-flight. We conclude that modulation of muscle sympathetic neural outflow by muscle metaboreceptors and skin nociceptors is preserved during short duration spaceflight.
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Affiliation(s)
- Qi Fu
- Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, 7232 Greenville Avenue, Suite 435, Dallas, TX 75231, USA
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Schobel HP, Frank H, Naraghi R, Geiger H, Titz E, Heusser K. Hypertension in patients with neurovascular compression is associated with increased central sympathetic outflow. J Am Soc Nephrol 2002; 13:35-41. [PMID: 11752019 DOI: 10.1681/asn.v13135] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Recent data suggest a causal relationship between essential hypertension and neurovascular compression (NVC) at the rostral ventrolateral medulla. An increase of central sympathetic outflow might be an underlying pathomechanism. The sympathetic nerve activity to muscle was recorded in 21 patients with hypertension with NVC (NVC+ group) and in 12 patients with hypertension without NVC (NVC- group). Heart rate variability, respiratory activity, BP, and central venous pressure at rest and during unloading of cardiopulmonary baroreceptors with lower-body negative pressure and during a cold pressor test were also measured. Resting sympathetic nerve activity to muscle was twice as high in the NVC+ group compared with the NVC- group (34 +/- 22 versus 18 +/- 6 bursts/min; P < 0.05). Resting heart rate (P = 0.06) and low- to high-frequency power ratio values (P = NS) (as indicators of cardiac sympathovagal balance) tended to be augmented as well in the NVC+ group. The sympathetic nerve activity to muscle response to the cold pressor test was increased in the NVC+ group versus the NVC- group (+15 +/- 11 versus 6 +/- 12 bursts/min; P = 0.05), but hemodynamic and sympathetic nerve responses to lower-body negative pressure did not differ between the two groups. It is concluded that NVC of the rostral ventrolateral medulla in patients with essential hypertension is accompanied by increased central sympathetic outflow. Therefore, these data support the hypothesis described in the literature: in a subgroup of patients, essential hypertension might be causally related to NVC of the rostral ventrolateral medulla, at least in part, via an increase in central sympathetic outflow.
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Affiliation(s)
- Hans P Schobel
- *Medical Clinic IV, Division of Nephrology and Hypertension, and Department of Neurosurgery, University of Erlangen-Nuremberg, Germany; and Medical Clinic, Division of Nephrology and Hypertension, University of Frankfurt, Germany
| | - Helga Frank
- *Medical Clinic IV, Division of Nephrology and Hypertension, and Department of Neurosurgery, University of Erlangen-Nuremberg, Germany; and Medical Clinic, Division of Nephrology and Hypertension, University of Frankfurt, Germany
| | - Ramin Naraghi
- *Medical Clinic IV, Division of Nephrology and Hypertension, and Department of Neurosurgery, University of Erlangen-Nuremberg, Germany; and Medical Clinic, Division of Nephrology and Hypertension, University of Frankfurt, Germany
| | - Helmut Geiger
- *Medical Clinic IV, Division of Nephrology and Hypertension, and Department of Neurosurgery, University of Erlangen-Nuremberg, Germany; and Medical Clinic, Division of Nephrology and Hypertension, University of Frankfurt, Germany
| | - Elmar Titz
- *Medical Clinic IV, Division of Nephrology and Hypertension, and Department of Neurosurgery, University of Erlangen-Nuremberg, Germany; and Medical Clinic, Division of Nephrology and Hypertension, University of Frankfurt, Germany
| | - Karsten Heusser
- *Medical Clinic IV, Division of Nephrology and Hypertension, and Department of Neurosurgery, University of Erlangen-Nuremberg, Germany; and Medical Clinic, Division of Nephrology and Hypertension, University of Frankfurt, Germany
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13
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Tsukiyama Y, Kuboki T, Clark GT. Cold pressor stimulation effect on hemodynamic changes following sustained isometric contraction in human jaw-closure muscles. J Dent Res 1999; 78:1727-34. [PMID: 10576169 DOI: 10.1177/00220345990780111001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
It is postulated that an altered adrenergic response pattern may be associated with chronic muscle pain states. To evaluate this hypothesis, one must fully understand the effect of an adrenergic activation on masticatory muscle blood flow under various conditions. This study evaluated the effect of a 12 degrees C cold pressor stimulation (a mild adrenergic activator), applied to the hand-forearm area, on intramuscular hemodynamics in the human masseter and temporalis muscles following a sustained isometric contraction. We assessed hemodynamics by measuring intramuscular hemoglobin concentration repeatedly, using a non-invasive near-infrared spectroscopy device. Measurements were taken before, during, and after a 30-second sustained 50% maximum voluntary contraction task. Fourteen healthy subjects, seven males and seven females, with no history of muscle pain in the masticatory system participated in this study. This protocol was repeated three times, but in the second trial, the cold pressor stimulation was applied to the subject during and for 5 min after the sustained contraction task. Repeated-measure analysis of variance performed on these data revealed that the peak hemoglobin concentration levels in the post-contraction recovery period were significantly reduced (between 13 and 14%) with cold pressor stimulation, both in the masseter (p < 0.001) and in the temporalis (p < 0.001) muscles. The results suggest that cold pressor stimulation produced a reduced intramuscular vasodilative response in these muscles during the immediate post-contraction period. One explanation for these results is that altering the local chemical environment of the muscle affects the adrenergic response pattern typically induced by a cold pressor stimulation.
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Affiliation(s)
- Y Tsukiyama
- UCLA School of Dentistry, Oral Medicine and Orofacial Pain, Los Angeles, California 90095-1668, USA
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14
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Acero CO, Kuboki T, Maekawa K, Yamashita A, Clark GT. Haemodynamic responses in chronically painful, human trapezius muscle to cold pressor stimulation. Arch Oral Biol 1999; 44:805-12. [PMID: 10530913 DOI: 10.1016/s0003-9969(99)00082-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The aim was to compare haemodynamic responses in trapezius muscles to cold pressor stimulation in individuals with localized trapezius myalgia and asymptomatic controls. Nine males with chronic localized pain in the trapezius (mean age, 23.2 years) and nine male controls (mean age, 24.6 years) who had no medical history of migraine, hypertension or sustained pain in the trapezius region were investigated. Two experimental (cold pressor and mock) trials were performed in a randomly assigned sequence. In the cold pressor trial the participant's left foot and ankle were immersed in 4 degrees C cold water for 2 min; the mock trial was done without that stimulus. Blood volume was continuously recorded 1 min before, 2 min during, and 5 min after cold pressor stimulation using near-infrared spectroscopy. Each participant's blood-volume data were baseline-corrected and submitted to statistical analysis. Results showed that the individuals with muscle pain exhibited a significantly lower mean blood volume than the controls during cold pressor stimulation (p = 0.0367). Upon withdrawal of that stimulation, the mean blood volume in both groups fell below the baseline. These results suggest that individuals with chronic regional trapezius myalgia have less capacity to vasodilate this muscle during cold pressor stimulation than those without such myalgia. It is not yet known if this difference in the haemodynamic response is a cause or an effect of the myalgia.
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Affiliation(s)
- C O Acero
- Department of Fixed Prosthodontics, Okayama University Dental School, Japan.
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15
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Micieli G, Cavallini A, Bosone D, Castellano AE, Nappi G. Bromocriptine test in the evaluation of patients with syncope of unknown aetiology. A case-control study. Acta Neurol Scand 1999; 99:297-302. [PMID: 10348159 DOI: 10.1111/j.1600-0404.1999.tb00679.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The aim of the present study was to evaluate, through a case-control study, the specificity of the upright tilt test with bromocriptine as a marker of neurally mediated syncope of unknown aetiology. We have compared upright tilt test with bromocriptine (2.5 mg p.o.) in patients with syncope of unknown aetiology and controls. A total of 23 patients and controls matched by age and sex had upright tilt test with bromocriptine. The upright tilt test procedure consisted of 10 min in supine position, 10 min of 60 degree head-up tilt and a further 10 min with the subject supine; this procedure was performed in baseline condition and 60, 120, 180 and 240 min after the administration of bromocriptine. The protocol end points were the development of syncope or presyncope in association with hypotension with or without bradycardia. A positive response to bromocriptine test was found in 78% (95% CI, 61% to 95%) of patients and in 13% (95% CI, 0% to 26%) of controls (P<0.001). No significant differences were detectable among patients and controls showing a positive response to the test. Bromocriptine test seems to be a useful alternative tool for the diagnosis of neuromediated syncope also suggesting that dopaminergic supersensitivity may, at various and to varying degrees, play a role in the pathogenesis of syncopal episodes.
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Affiliation(s)
- G Micieli
- Dept of Neurology, IRCCS C. Mondino, Pavia, Italy
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16
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Schobel HP, Handwerker HO, Schmieder RE, Heusser K, Dominiak P, Luft FC. Effects of naloxone on hemodynamic and sympathetic nerve responses to pain in normotensive vs. borderline hypertensive men. JOURNAL OF THE AUTONOMIC NERVOUS SYSTEM 1998; 69:49-55. [PMID: 9672123 DOI: 10.1016/s0165-1838(98)00005-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Pain sensitivity decreases with increasing resting blood pressure. This blood pressure-pain interaction may be mediated by endogenous opioids which have been shown to affect both blood pressure and nociception. To test this hypothesis, we measured mean arterial blood pressure (MAP), central venous pressure (CVP), heart rate (HR), muscle sympathetic nerve activity (MSNA), serum catecholamines, and individual pain rating scales during 2 min periods of noxious mechanostimulation (skin fold pinching) in nine young (26 +/- 2 year), male normotensive (NT) subjects and in 12 age and weight matched males with borderline hypertension (BHT). Measurements were performed before and after the i.v. administration of naloxone (0.15 mg/kg) and placebo in a randomized double-blind cross-over trial. In the pre-naloxone trials, pain led to similar changes in MAP, CVP, MSNA and plasma catecholamines in the two groups except for a higher increase in HR in the BHT group as compared to the NT group (3 +/- 1 vs. 1 +/- 1 bpm; P < 0.005). Opioid blockade with naloxone increased MSNA responses to pain in the NT group (from 5 +/- 1 to 9 +/- 1 bursts/min, and, from 100 +/- 23 to 204 +/- 36 units/min, respectively; P < 0.05) but did not significantly affect the MSNA response to pain in the BHT group. Pain induced responses of MAP, CVP, and catecholamines were not altered by naloxone in either group. Overall, there was a highly significant inverse correlation between pain perception and resting blood pressure which was not significantly affected by naloxone. The BHT subjects exhibited a lower pain perception compared to the NT subjects (P < 0.005). Naloxone increased pain rating in the NT group (from 194 +/- 9 to 218 +/- 13; P < 0.005) but not in the borderline hypertensive group (160 +/- 8 vs. 168 +/- 10; P = 0.36). Except for a decreased HR response in the BHT group, placebo had no effect on the responses to pain. Our data do not indicate a major role of the endogenous opioid system for the blood pressure-pain interaction in man. Endogenous opioids affect pain perception and sympathetic nerve activity responses to pain in normotensive men but their activity seems to be attenuated in borderline hypertensive subjects. Therefore, the lower pain sensitivity in human essential hypertension is probably mediated by non-opioid mechanisms.
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Affiliation(s)
- H P Schobel
- Medical Clinic IV-Nephrology, University of Erlangen-Nürnberg, Erlangen, Germany
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17
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Mannelli M, Lazzeri C, Ianni L, La Villa G, Pupilli C, Bellini F, Serio M, Franchi F. Dopamine and sympathoadrenal activity in man. Clin Exp Hypertens 1997; 19:163-79. [PMID: 9028644 DOI: 10.3109/10641969709080813] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The sympathetic adrenal (SA) activity can be modulated by dopamine (DA) through D2 receptors. In man, using D2 antagonists, it has been demonstrated that endogenous DA plays an inhibitory modulation of the SA system during high degree of SA activation. D2 agonists are able to induce a decrease in norepinephrine (NE) release either in vitro or in vivo. This effect leads, in vivo, to a decrease in blood pressure (BP) and to an activation of arterial baroreceptors. Therefore, in vivo, the D2 mediated inhibition of epinephrine (E) release, which is clearly demonstrated in vitro, is overwhelmed by the baroreceptor-mediated activation of the splachnic nerve. As a consequence, the in vivo administration of D2 agonists can induce a different effect on the net peripheral sympathetic tone of an organ, depending on the balance between the degree of the baroreceptor-mediated sympathetic activation and the inhibitory D2-mediated inhibition of NE release at the tissue level. In the present paper we investigated the in vivo effect of placebo (PL) or acute oral bromocriptine (BC) administration on plasma CA and on the cardiac sympatho-vagal balance of 7 normal volunteers, as assessed by power spectral analysis of heart rate (HR) variability (autoregressive method), either in resting or sitting position. Low frequency (LF) and high frequency (HF) components, both expressed in normalized units (nU), and LF/HF ratio were calculated. BC caused a decrease in BP, plasma NE and no change in HR in resting and sitting position. Plasma E increased in sitting position. At the heart level, after BC, we observed, during rest, an increase in LF and LF/HF ratio and a decrease in HF while in sitting position LF did not increase further. These data show that BC, while reducing BP through a decrease of plasma NE, increases LF/HF ratio (sympathetic tone) without any change in heart rate. These data seem to confirm that BC causes an inhibitory modulation of the SA system acting predominantly at the periphery through D2 presynaptic receptors.
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Affiliation(s)
- M Mannelli
- Department of Clinical Pathophysiology, University of Florence, Italy
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Schobel HP, Ringkamp M, Behrmann A, Forster C, Schmieder RE, Handwerker HO. Hemodynamic and sympathetic nerve responses to painful stimuli in normotensive and borderline hypertensive subjects. Pain 1996; 66:117-24. [PMID: 8880832 DOI: 10.1016/0304-3959(96)03079-5] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Observations in animals and humans show that pain sensitivity might be lower (and pain tolerance higher) in hypertensive as compared to normotensive subjects. One hypothesis, derived from experimental studies, assumes that enhanced activation of baroreceptors leads to an enhanced central inhibition. A central hypothesis assumes changes in the central (endogenous) control of the nociceptive system. To investigate these two hypotheses we quantitatively assessed the minute-by-minute changes in mean arterial pressure (MAP), central venous pressure (CVP) heart rate (HR), muscle sympathetic nerve activity (MSNA), and individual pain ratings during noxious mechanostimulation in 10 normotensive (NT) and 13 borderline hypertensive (BH) subjects. Linear regression analysis indicated a close negative correlation for the overall data between resting levels of MAP and pain ratings (r = -0.57, P < 0.0001). The BH group exhibited a lower pain sensitivity compared to the NT group (P < 0.001). The extent of baroreceptor activation during the application of pain was not different between the two groups (P = NS) as assessed by almost identical increases in MAP (+8 +/- 1 vs. +9 +/- 1 mmHg NT vs. BH group), CVP (+0.7 +/- 0.1 vs. +0.5 +/- 0.1 mmHg), HR (+2 +/- 1 vs. +2 +/- 1 beats/min), and MSNA (+5 +/- 1 +4 +/- 1 bursts/min). The NT subjects exhibited significant correlations between the pain ratings and the increases in MAP (r = +0.52; P < 0.05) and MSNA (r = +0.49; P < 0.05) whereas the BH subjects did not show such a relationship. Thus, the increased pain tolerance in human hypertension cannot be explained by hemodynamically mediated differences in the activation of baroreceptors or by an altered baroreflex sensitivity during the application of pain. We conclude, that the reduced pain sensitivity in hypertensive humans is more likely related to central changes.
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Affiliation(s)
- H P Schobel
- Department of Internal Medicine, University of Erlangen-Nürnberg, Germany
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