PubMed Health⌕ Search

Biomedical subjects

Krzysztof Narkiewicz

Publications and source records attributed to Krzysztof Narkiewicz.

At least 19 recordsLinked to original sources
PubMed2007

Tonic chemoreflex activation contributes to the elevated muscle sympathetic nerve activity in patients with chronic renal failure.

OBJECTIVE: Sympathetic activation may contribute to both cardiovascular morbidity and the progression of chronic kidney disease. The role of the chemoreceptors in determining sympathetic nerve discharge in patients with chronic renal failure (CRF) is unknown. We tested the hypothesis that tonic activation of excitatory chemoreceptor afferents contributes to the elevated sympathetic activity in patients with CRF. METHODS: Utilizing a double-blind, randomized, vehicle-controlled design, we examined the effects of chemoreflex deactivation on muscle sympathetic nerve activity (MSNA). We compared effects of breathing 100% oxygen for 15 min with effects of breathing room air for 15 min in 12 stable patients with CRF and in 12 control individuals with similar age, gender, blood pressure and body mass index. RESULTS: The baseline MSNA was elevated significantly in the patients with CRF as compared with the control individuals (50 +/- 2 vs 42 +/- 2 bursts/min; P < 0.05). Reductions in systolic blood pressure and pulse pressure in response to the administration of 100% oxygen were significantly different from those observed during administration of room air in patients with CRF. In patients with CRF, MSNA decreased by 29 +/- 7% (P < 0.01) during hyperoxia but did not change during administration of room air (5 +/- 6%; P = NS). By contrast, neither 100% oxygen or room air changed any measures in control individuals. CONCLUSIONS: Tonic activation of excitatory chemoreflex afferents contributes to increased efferent sympathetic activity to muscle circulation and to blood pressure control in patients with CRF. These findings may have important implications for understanding mechanisms underlying the link between CRF and cardiovascular disease.

Administration, Inhalation↗
PubMed2007

beta-2-adrenergic receptor gene polymorphism confers susceptibility to Graves disease.

Graves disease (GD) is an autoimmune disorder with genetic predisposition. The polymorphisms 47A-->G (Arg16Gly) and 79C-->G (Gln27Glu) of the adrenergic beta-2 receptor (ADRB2) gene in the 5q32 region affect the functional reaction to adrenergic stimulation, which contributes to the regulation of immunological response. The -367T-->C polymorphism within the 5'-leading regulatory sequence affects ADRB2 transcriptional activity. The aim of the present study was to investigate whether ADRB2 gene variants are associated with susceptibility to GD. All polymorphisms were studied in Polish GD patients (n=300) and healthy control subjects without a family history of autoimmune disorders (n=301). Genotypes were determined by the MassARRAY system (Sequenom, San Diego, CA). Gly16 and Gln27 allele frequencies were 61.4% and 55.2% among healthy controls, almost the same as previously reported in 4441 white participants of a cardiovascular health study. We found a higher risk of GD in Gln27 carriers (CC or CG genotypes) than in Glu27 homozygous (GG genotype) participants (OR=1.99, 95% CI: 1.27-3.12, p=0.003, pcorr=0.03). The frequency of the 79GG protective genotype was significantly smaller in the GD patients without symptoms of Graves ophthalmopathy compared to controls (10% vs 22%, OR=0.41, 95% CI: 0.234-0.706, p=0.0017, pcorr=0.015). We didn't find any association of -367T--> or 47A-->G genotypes/alleles with Graves disease, however, haplotype analysis has shown a significant difference in haplotype distribution between patients and controls (the global p=0.001) with increased -367T/47A/79C haplotype frequency in GD patients compared to controls (34% vs 25%, p=0.00073, pcorr=0.0044). In conclusion, Gln27 carriers (79CC or 79GC genotypes) have increased risk of Graves disease. Our results suggest that ADRB2 plays a role in susceptibility to Graves disease in humans.

Adolescent↗
PubMed2006

Sympathetic neural responses to smoking are age dependent.

OBJECTIVE: Smoking is an important risk factor for cardiovascular disease. Sympathetic responses to cigarette smoking may be implicated in the link between smoking and cardiovascular disease. We tested the hypothesis that the sympathetic neural responses to smoking are age dependent. METHODS: We examined the effects of cigarette smoking and sham smoking on muscle sympathetic nerve activity, blood pressure and heart rate in 14 normotensive middle-aged (49 +/- 4 years) and 12 young (29 +/- 4 years) habitual smokers matched for body mass index (25 +/- 2 kg/m2 in both groups). RESULTS: Sham smoking had no significant effect on sympathetic drive, blood pressure or heart rate in either group. Cigarette smoking increased heart rate in both middle-aged subjects and young subjects. In comparison to younger subjects, middle-aged smokers showed similar smoking-related increases in systolic blood pressure (SBP) [10 +/- 3 versus 12 +/- 2 mmHg, respectively, not significant (NS)]. Smoking decreased sympathetic nerve activity by 28 +/- 12% of baseline values (P < 0.01) in young subjects. However, muscle sympathetic nerve activity did not change significantly after smoking in middle-aged subjects (5 +/- 8%, NS), despite the increased blood pressures, which would be expected to inhibit sympathetic activity. By contrast, in young subjects, the heart rate increase (22 +/- 2 bpm) was greater than that seen in middle-aged subjects (13 +/- 2 bpm, P < 0.01). CONCLUSIONS: The autonomic responses to smoking are age dependent. While blood pressure increases are similar in both groups, young subjects respond to smoking by marked increases in heart rate and suppression of central sympathetic outflow. In middle-aged subjects, the heart rate increase is less marked, but sympathetic vasoconstrictor activity is not suppressed.

Adult↗
PubMed2006

Attempt to eliminate health inequalities in Poland arising at the time of political and economic transformation: Polish 400 Cities Project.

AIM: Epidemiological data show that citizens of small towns and villages have presented worse trends in cardiovascular mortality during the political, social and economic transformation in Poland during past 15 years than citizens of large towns. To try to eliminate these inequalities the Polish 400 Cities Project (P400CP), a large educational and interventional project, was prepared. The project consists of two arms: medical and social interventions. MATERIAL AND METHODS: The main aim of the medical screening intervention in P400CP is to increase detection and control of cardiovascular risk factors in inhabitants of 418 small cities (<8000 inhabitants) and surrounding villages, particularly in men and people of lower education. In 2003 and 2004 the P400CP covered 123 cities. All together, 36 696 subjects aged between 18 and 98 years were examined. In all participants, blood pressure (BP), anthropometric measurements, laboratory tests and questionnaire interviews were performed. The social arm of P400CP is one of multi-level educational intervention. Modern techniques of social psychology and marketing were involved to increase participation in interventions. RESULTS: Only 12.5% of all subjects had normal BP, cholesterol (<190 mg/dl) and glucose (<100 mg/dl in whole capillary blood) levels. During the first screening visit 65.5% of all examined subjects had BP>/=140 mmHg or >/=90 mmHg. The fasting glucose level was increased in 19% of women and 26% of men. Almost two-third of all subjects had a total cholesterol level above the norm. CONCLUSIONS: The prevalence of cardiovascular risk factors in participants of the screening programme P400CP in small towns in Poland was very high. High prevalence and low control of risk factors in participants of the P400CP confirm the decision to target this programme at citizens of small towns and villages.

Adolescent↗
PubMed2006

Antihypertensive therapy in the obese hypertensive patient.

PURPOSE OF REVIEW: Obesity is becoming recognized as one of the most important risk factors for the development of hypertension. The purpose of the review is to examine the latest evidence linking hypertension to obesity, summarize the benefits of weight reduction and present results of recent clinical trials evaluating antihypertensive treatment in obese patients. RECENT FINDINGS: Adipose tissue has been directly implicated in the pathogenesis of hypertension. Obesity has been associated with unequivocal changes in cardiovascular structure and function. In contrast to earlier studies, several recent trials included overweight and obese patients. Evidence of potential benefits of angiotensin blockade in the management of obesity hypertension is growing. Hypertension management in obese individuals is complicated by poorer response to treatment, and the increased need for multiple medications. It is important to consider obstructive sleep apnea in obese patients with resistant hypertension. SUMMARY: Several new lines of evidence suggest that drugs blocking the renin-angiotensin system might be considered as first-line therapy of obesity-related hypertension. Recent progress in understanding the mechanisms of obesity and associated disease processes might lead to development of novel therapeutic strategies. Further research in this area holds great promise for prevention of obesity-related cardiovascular disease.

Antihypertensive Agents↗
PubMed2005

Sympathetic neural outflow and chemoreflex sensitivity are related to spontaneous breathing rate in normal men.

Respiration contributes importantly to short-term modulation of sympathetic nerve activity. However, the relationship between spontaneous breathing rate, chemoreflex function, and direct measures of sympathetic traffic in healthy humans has not been studied previously. We tested the hypothesis that muscle sympathetic nerve activity and chemoreflex sensitivity are linked independently to respiratory rate in normal subjects. We studied 69 normal male subjects aged 29.6+/-8.1 years. Subjects were subdivided according to the tertiles of respiratory rate distributions. Mean respiration rate was 10.6 breaths/min in the first tertile, 14.8 breaths/min in the second tertile, and 18.0 breaths/min in the third tertile. Subjects from the third tertile (faster respiratory rate) had greater sympathetic activity than subjects from the first tertile (slower respiratory rate; 29+/-3 versus 17+/-2 bursts/min; P<0.001). Stepwise multiple linear regression analysis revealed that only respiratory rate was linked independently to sympathetic activity (r=0.42; P<0.001). In comparison to subjects with slow respiratory rate, subjects with fast respiratory rate had greater increases in minute ventilation during both hypercapnia (7.3+/-0.8 versus 3.2+/-1.0 L/min; P=0.005) and hypoxia (5.7+/-0.8 versus 2.4+/-0.7 L/min; P=0.007). Muscle sympathetic nerve activity and chemoreflex sensitivity are linked to spontaneous respiratory rate in normal humans. Faster respiratory rate is associated with higher levels of sympathetic traffic and potentiated responses to hypoxia and hypercapnia. Spontaneous breathing frequency, central sympathetic outflow, and chemoreflex sensitivity exhibit significant and hitherto unrecognized interactions in the modulation of neural circulatory control.

Adult↗
PubMed2005

Effects of peripheral chemoreceptors deactivation on sympathetic activity in heart transplant recipients.

Heart transplantation initially normalizes sympathetic hyperactivity directed at the muscle circulation. However, sympathetic activity increases with time after transplantation and the exact mechanisms responsible for sympathetic control in heart transplant recipients remain unclear. We examined the effects of peripheral chemoreflex deactivation caused by breathing 100% oxygen on muscle sympathetic nerve activity (expressed as number of burst per minute and mean burst amplitude), heart rate, and mean blood pressure in 13 heart transplant recipients, 13 patients with essential hypertension, and 10 controls. Heart transplant recipients disclosed the highest sympathetic activity, whereas it did not differ between controls and patients with essential hypertension (51+/-16 versus 37+/-14 versus 39+/-12 burst/min, respectively; P<0.05). Breathing 100% oxygen, in comparison with 21% oxygen, reduced sympathetic activity (-4+/-4 versus -1+/-2 burst/min, P<0.01; 85+/-9 versus 101+/-8% of amplitude at baseline, P<0.001) and mean blood pressure (-4+/-5 versus +3+/-6 mm Hg; P<0.05) in heart transplant recipients, decreased sympathetic activity (-4+/-4 versus 0+/-3 burst/min, P<0.05; 90+/-16 versus 101+/-9% of amplitude at baseline, P<0.05) in patients with essential hypertension, but did not reduce sympathetic activity (2+/-4 versus 3+/-3 burst/min, P=NS; 95+/-11 versus 95+/-13% of amplitude at baseline, P=NS) in control subjects. The sympathetic response to hyperoxia was more marked in heart transplant recipients than in controls (85+/-9 versus 95+/-11% of baseline amplitude; P<0.05). The decrease in sympathetic activity was most evident in patients with the longest time after heart transplantation (r=-0.75, P<0.01). In conclusion, tonic chemoreflex activation increases resting muscle sympathetic nerve activity and favors blood pressure elevation after heart transplantation.

Administration, Inhalation↗
PubMed2005

Hemodynamic and autonomic effects of smokeless tobacco in healthy young men.

OBJECTIVES: The aim of this study was to investigate the acute hemodynamic and autonomic effects of smokeless tobacco. BACKGROUND: Smokeless tobacco use is increasing. Its cardiovascular effects are not well understood. METHODS: Sixteen healthy, male, habitual snuff tobacco users (aged 22 +/- 1 year) were studied, using a randomized, double-blind, placebo-controlled, crossover design with two separate experimental sessions: placebo and tobacco. Muscle sympathetic nerve activity (MSNA), electrocardiogram, blood pressure, calf blood flow, nicotine, and catecholamines were measured. RESULTS: Snuff tobacco increased plasma nicotine from 2.8 +/- 0.5 ng/ml to 10.4 +/- 1.1 ng/ml. Mean blood pressure increased by 10 +/- 1 mm Hg, and heart rate increased by 16 +/- 2 beats/min. Peripheral vascular resistance, MSNA, and norepinephrine concentration did not change with tobacco, but epinephrine increased by approximately 50%. CONCLUSIONS: Oral snuff tobacco increases heart rate, blood pressure, and epinephrine. Despite the increase in blood pressure, there is no decrease in either MSNA or peripheral vascular resistance. Smokeless tobacco is a powerful autonomic and hemodynamic stimulus. Catecholamine release from the adrenal medulla likely contributes to this response.

Adult↗
PubMed2005

Gender-selective interaction between aging, blood pressure, and sympathetic nerve activity.

The mechanisms mediating the more striking age related increase in cardiovascular disease in women than in men are poorly understood. We tested the hypothesis that aging has a greater impact on sympathetic traffic in women than in men. Muscle sympathetic nerve activity (MSNA), blood pressure, and heart rate were measured in 120 healthy males and 96 healthy females aged 20 to 72 years. MSNA increased with age in both sexes, but age explained 53% of MSNA variance in female subjects and only 8% of MSNA variance in male subjects. Both the slope and intercept of the regression lines were significantly different between male and female groups (P<0.01 and P<0.001, respectively). For each decade of life, women showed an increase of 6.5 bursts/min in comparison to an increase of 2.6 bursts/min in males. Menopause did not explain the age-related increase in sympathetic traffic. For every 10-burst/min increment in MSNA in subjects older than 40, mean blood pressure increased by 2.7 mm Hg in men and by 6.1 mm Hg in women. Aging is accompanied by a greater increase in sympathetic traffic in women than in men, independent of menopausal status. Sympathetic neural mechanisms may contribute importantly to the more marked influence of age on blood pressure and cardiovascular disease in women.

Adult↗
PubMed2005

Obstructive sleep apnea and hypertension.

There is growing evidence of a causal relationship between obstructive sleep apnea (OSA) and hypertension. Untreated OSA may have direct and deleterious effects on cardiovascular function and structure through several mechanisms, including sympathetic activation, oxidative stress, inflammation, and endothelial dysfunction. OSA may contribute to or augment elevated blood pressure levels in a large proportion of the hypertensive patient population. It is important to consider OSA in the differential diagnosis of hypertensive patients who are obese. OSA should be especially considered in those hypertensive patients who respond poorly to combination therapy with antihypertensive medications.

Animals↗