Endothelial dysfunction in human hand veins is rapidly reversible after smoking cessation

[Influence of smoking cessation on the microcirculatory bed in apparently healthy young people]

AIM

To study the influence of smoking cessation on the microcirculatory bed (MCB) in 33 healthy young people.

SUBJECTS AND METHODS

The investigation enrolled 33 healthy young people (male/female (M/F) ratio, 20:13; mean age, 21.6±0.5 years) who had quit smoking 1 month to 10 years (mean age 2.5±0.5 years) before. Comparable groups consisted of 15 smokers (M/F ratio, 5:10; mean age, 21.5±0.8 years) and 18 nonsmokers (M/F ratio, 6:12; mean age, 21±0.3 years). Computer-assisted video-biomicroscopy of the bulbar conjunctiva was carried out. When assessing the

RESULTS

attention was focused on microvessel diameter changes in the patients who had quit smoking compared to the smokers and nonsmokers.

RESULTS

As compared to the smokers, those who had quit smoking showed a significant increase in the mean diameters of arterioles (13.01±0.41 and 18.33±0.65 µm; р<0.001) and capillaries (9.2±0.23 and 9.89±0.19 µm; р<0.05). The number of functioning capillaries per mm2 of the conjunctival surface did not differ from that in the nonsmokers (8.01±0.21 and 8.25±0.44; р>0.05). Thus, the rarefication phenomenon reflecting the influence of smoking on the MCB vessels at a young age undergoes rapidly regression. There are increases in the diameter of arterioles and the number of functioning capillaries just in the first months of smoking cessation (р<0.01).

CONCLUSION

The considerably increased diameters of arterioles and capillaries and the larger number of functioning capillaries per mm2 of the conjunctival surface suggest that smoking cessation at a young age have a positive impact on MCB vessels.

Risk of Heart Failure and Death After Prolonged Smoking Cessation: Role of Amount and Duration of Prior Smoking

BACKGROUND

According to the 2004 Surgeon General's Report on Health Consequences of Smoking, after >15 years of abstinence, the cardiovascular risk of former smokers becomes similar to that of never-smokers. Whether this health benefit of smoking cessation varies by amount and duration of prior smoking remains unclear.

METHODS AND RESULTS

Of the 4482 adults ≥65 years without prevalent heart failure (HF) in the Cardiovascular Health Study, 2556 were never-smokers, 629 current smokers, and 1297 former smokers with >15 years of cessation, of whom 312 were heavy smokers (highest quartile; ≥32 pack-years). Age-sex-race-adjusted hazard ratios (aHR) and 95% confidence intervals (CI) for centrally adjudicated incident HF and mortality during 13 years of follow-up were estimated using Cox regression models. Compared with never-smokers, former smokers as a group had similar risk for incident HF (aHR, 0.99; 95% CI, 0.85-1.16) and all-cause mortality (aHR, 1.08; 95% CI, 0.96-1.20), but former heavy smokers had higher risk for both HF (aHR, 1.45; 95% CI, 1.15-1.83) and mortality (aHR, 1.38; 95% CI, 1.17-1.64). However, when compared with current smokers, former heavy smokers had lower risk of death (aHR, 0.64; 95% CI, 0.53-0.77), but not of HF (aHR, 0.97; 95% CI, 0.74-1.28).

CONCLUSIONS

After >15 years of smoking cessation, the risk of HF and death for most former smokers becomes similar to that of never-smokers. Although this benefit of smoking cessation is not extended to those with ≥32 pack-years of prior smoking, they have lower risk of death relative to current smokers.

Smoking cessation reverses DNA double-strand breaks in human mononuclear cells

OBJECTIVE

Cigarette smoking is a major risk factor for atherosclerotic cardiovascular disease, which is responsible for a significant proportion of smoking-related deaths. However, the precise mechanism whereby smoking induces this pathology has not been fully delineated. Based on observation of DNA double-strand breaks (DSBs), the most harmful type of DNA damage, in atherosclerotic lesions, we hypothesized that there is a direct association between smoking and DSBs. The goal of this study was to investigate whether smoking induces DSBs and smoking cessation reverses DSBs in vivo through examination of peripheral mononuclear cells (MNCs).

APPROACH AND RESULTS

Immunoreactivity of oxidative modification of DNA and DSBs were increased in human atherosclerotic lesions but not in the adjacent normal area. DSBs in human MNCs isolated from the blood of volunteers can be detected as cytologically visible "foci" using an antibody against the phosphorylated form of the histone H2AX (γ-H2AX). Young healthy active smokers (n = 15) showed increased γ-H2AX foci number when compared with non-smokers (n = 12) (foci number/cell: median, 0.37/cell; interquartile range [IQR], 0.31-0.58 vs. 4.36/cell; IQR, 3.09-7.39, p<0.0001). Smoking cessation for 1 month reduced the γ-H2AX foci number (median, 4.44/cell; IQR, 4.36-5.24 to 0.28/cell; IQR, 0.12-0.53, p<0.05). A positive correlation was noted between γ-H2AX foci number and exhaled carbon monoxide levels (r = 0.75, p<0.01).

CONCLUSIONS

Smoking induces DSBs in human MNCs in vivo, and importantly, smoking cessation for 1 month resulted in a decrease in DSBs to a level comparable to that seen in non-smokers. These data reinforce the notion that the cigarette smoking induces DSBs and highlight the importance of smoking cessation.

Effects of recombinant human thyrotropin administration on 24-hour arterial pressure in female undergoing evaluation for differentiated thyroid cancer

Objective. Thyroid-stimulating-hormone (TSH) receptors are expressed in endothelial cells. We investigated whether elevated TSH levels after acute recombinant TSH (rhTSH) administration may result in alterations in blood pressure (BP) in premenopausal women with well-differentiated thyroid carcinoma (DTC). Designs. Thirty euthyroid DTC female patients were evaluated by rhTSH stimulation test (mean age 40.4 ± 8.6 years). A 24 h ambulatory systolic and diastolic blood pressure (SBP, DBP) monitoring (24 hr ABPM) was performed on days 2-3(D2-3). TSH was measured on day 1(D1), day 3(D3), and day 5(D5). Central blood pressure was evaluated on D3. Twenty-three patients were studied 1-4 weeks earlier (basal measurements). Results. TSH levels were D1: median 0.2 mU/L, D3: median 115.0 mU/L, and D5: median 14.6 mU/L. There were no significant associations between TSH on D1 and D3 and any BP measurements. Median D5 office-SBP and 24 h SBP, DBP, and central SBP were correlated with D5-TSH (P < 0.04). In those where a basal 24 h ABPM had been performed median pulse pressure was higher after rhTSH-test (P = 0.02). Conclusions. TSH, when acutely elevated, may slightly increase SBP, DBP, and central SBP. This agrees with previous reports showing positive associations of BP with TSH.

Assessment of endothelial dysfunction in health and disease; using various parameters

Conditions like hypertension, atherosclerosis and diabetes are known to be the result of endothelial dysfunction which could begin early in the life of an individual. The markers of endothelial dysfunction studied in the present work are plasma hemoglobin, serum high sensitivity C-reactive protein (hsCRP) and plasma nitrite and nitrate. We studied the onset of endothelial dysfunction with increase in age as well as in disease condition like newly detected hypertensives and of hypertensive diabetic patients. The mean plasma hemoglobin and hsCRP values were found to increase with age. hsCRP and plasma hemoglobin levels were significantly higher in patient groups as compared to aged-matched controls. On the other hand nitrate and nitrite was significantly higher in patients who suffered from both diabetes and hypertension together and nitrate values were significantly lower in patients who suffered from hypertensive alone. Plasma hemoglobin and hsCRP are associated with endothelial dysfunction and increases both with age as well as in disease condition.

Only two-week smoking cessation improves platelet aggregability and intraplatelet redox imbalance of long-term smokers

OBJECTIVES

We investigated whether and how soon smoking cessation ameliorates the smoking-induced intracellular oxidative stress and platelet aggregability in long-term smokers.

BACKGROUND

Smoking is a major risk factor of atherothrombosis. Smoking cessation reduces cardiac events. However, the underlying mechanisms of the beneficial effects remain to be elucidated.

METHODS

Twenty-seven male long-term smokers were divided into two groups. Group A (n = 14) quit smoking for four weeks whereas group B (n = 13) resumed smoking two weeks after quitting. Smoking status was monitored by measurement of urinary cotinine. Using gel-filtered platelets, agonist (adenosine diphosphate and collagen)-induced platelet aggregation, platelet-derived nitric oxide (PDNO), intraplatelet nitrotyrosine production, intraplatelet levels of the reduced form of glutathione (GSH) and its oxidized form (GSSG), and urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) and urinary 8-iso-prostaglandin F(2alpha) (8-iso-PGF(2alpha)), as markers of systemic oxidative stress, were measured. The baseline measurements were similar between the two groups.

RESULTS

Smoking cessation quickly reduced agonist-induced platelet aggregations, intraplatelet nitrotyrosine level, and urinary productions of 8-OHdG and 8-iso-PGF(2alpha) by two weeks in both groups. In group A, they were maintained at the low levels until four weeks, whereas they were reversed by resmoking in group B; PDNO release and intraplatelet GSH/GSSG ratio were time-dependently increased by smoking cessation but reversed by resmoking.

CONCLUSIONS

The present findings are the first demonstration that only two weeks of smoking cessation can ameliorate the enhanced platelet aggregability and intraplatelet redox imbalance in long-term smokers, possibly by decreasing oxidative stress. Our findings may strengthen the motivation for smokers to quit smoking.

Sildenafil does not improve nitric oxide-mediated endothelium-dependent vascular responses in smokers

AIMS

To examine the hypothesis that sildenafil, a phosphodiesterase type 5 inhibitor that inhibits cGMP breakdown, could enhance nitric oxide-mediated vasodilation and reverse endothelial dysfunction in chronic smokers.

METHODS

Flow-mediated dilation of the brachial artery and forearm postischemic reactive hyperemia (both nitric oxide-mediated responses) were measured before and after sildenafil 50 mg and placebo in a double-blind, randomized, crossover study in 9 men who were chronic smokers (21 +/- 3 pack years).

RESULTS

There was no significant change in flow-mediated dilation after either sildenafil (0.18%, 95%CI -1.7-2%) or placebo (0.24%, 95%CI -2.8-3.3%) (P = 0.88 and 0.8, respectively). Sildenafil had no significant effect on resting forearm blood flow or postischemic reactive hyperemia (P = 0.39 and 0.7, respectively). Resting heart rate and blood pressure were unaffected by sildenafil.

CONCLUSIONS

Acute sildenafil administration did not improve endothelial function in chronic smoking men.

Effect of nicotine on vasoconstrictor and vasodilator responses in human skin vasculature

Our objective was to test the hypothesis that acute exposure of human skin vasculature to nicotine may have deleterious effects on endothelial function. Vasoconstriction and vasorelaxation in isolated perfused human skin flaps (approximately 8 x 18 cm) derived from dermolipectomy specimens were assessed by studying changes in skin perfusion pressure measured by a pressure transducer, and skin perfusion was assessed by a dermofluorometry technique (n = 4 or 5). It was observed that nicotine (10(-7) M) amplified (P < 0.05) the norepinephrine (NE)-induced concentration-dependent (10(-7)-10(-5) M) increase in skin vasoconstriction compared with the control. This amplification effect of nicotine in NE-induced skin vasoconstriction was not blocked by the nicotine-receptor antagonist hexamethonium (10(-6) M) or the cyclooxygenase inhibitor indomethacin (10(-5) M). It was also observed that ACh and nitroglycerin (NTG) elicited a concentration-dependent (10(-8)-10(-5) M) vasorelaxation in skin flaps preconstricted with 8 x 10(-7) M of NE. The vasorelaxation induced by ACh was attenuated (P < 0.05) in the presence of nicotine (10(-7) M) compared with the control. However, skin vasorelaxation induced by NTG was not affected by nicotine (10(-7) M). ACh and NTG are known to induce endothelium-dependent and -independent vasorelaxation, respectively. The present findings were interpreted to indicate that acute exposure of human skin vasculature to nicotine was associated with 1) amplification of NE-induced skin vasoconstriction and 2) impairment of endothelium-dependent skin vasorelaxation. Cyclooxygenase products and nicotine receptors blocked by hexamethonium were not involved in the amplification of NE-induced skin vasoconstriction by nicotine. These findings may provide further insight into the pathogenesis of skin vasospasm in skin flap surgery and skin ischemic disease associated with cigarette smoking or use of smokeless tobacco.