Download the Free Unbound MEDLINE PubMed App to your smartphone or tablet.
Available for iPhone, iPad, iPod touch, and Android.
- Vigorous Exercise Training Improves Reactivity of Cerebral Arterioles and Reduces Brain Injury Following Transient Focal Ischemia. [JOURNAL ARTICLE]
- Microcirculation 2014 Mar 12.
We examined whether vigorous exercise training (VExT) could influence nitric oxide synthase (NOS)-dependent vasodilation and transient focal ischemia-induced brain injury. Rats were divided into sedentary (SED) or VExT groups. Exercise was carried out 5 days/week for a period of 8-10 weeks. First, we measured responses of pial arterioles to an eNOS-dependent (ADP), an nNOS-dependent (NMDA) and a NOS-independent (nitroglycerin) agonist in SED and VExT rats. Second, we measured infarct volume in SED and VExT rats following middle cerebral artery occlusion (MCAO). Third, we measured superoxide levels in brain tissue of SED and VExT rats under basal and stimulated conditions. We found that eNOS- and nNOS-dependent, but not NOS-independent vasodilation, was increased in VExT compared to SED rats, and this could be inhibited with L-NMMA in both groups. In addition, we found that VExT reduced infarct volume following MCAO when compared to SED rats. Further, superoxide levels were similar in brain tissue from SED and VExT rats under basal and stimulated conditions. We suggest that VExT potentiates NOS-dependent vascular reactivity and reduces infarct volume following MCAO via a mechanism that appears to be independent of oxidative stress, but presumably related to an increase in the contribution of nitric oxide. This article is protected by copyright. All rights reserved.
- Calcitonin Gene-Related Peptide Protects the Myocardium From lschemia Induced by Endothelin-1: lntravital Microscopic Observation and (31)P-MR Spectroscopic Studies. [JOURNAL ARTICLE]
- Life Sci 2014 Mar 4.
Calcitonin gene-related peptide (CGRP) is a potent vasodilator neuropeptide. We investigated the ameliorating effect of CGRP in myocardial ischemia induced by endothelin-1 (ET-1), with special emphasis on myocardial microvascular hemodynamics and levels of energy-related metabolites.Langendorff preparations of rat isolated heart were perfused at a constant flow rate. Microvascular blood flow was also visualized in the anterior epicardium of the left ventricle by means of an intravital fluorescence microscope system. Energy-related metabolite contents in the myocardium were measured by means of (31)P-magnetic resonance spectroscopy ((31)P-MRS).Intracoronary bolus injections of CGRP caused dose-dependent decreases in coronary perfusion pressure (CPP) in hearts exposed to ET-1 (30 pmol). The vasodilator potency of CGRP was about 1000-fold greater than that of nitroglycerin and 100-fold greater than that of isobutylmethylxanthine. Vasodilation of the small-sized arterioles (10-40μm in diameter) in response to CGRP (100 pmol) was confirmed by direct microscopic observation. After ET-1 (30 pmol) plus vehicle administration, high energy phosphates (phosphocreatine (PCr), ATP) were markedly reduced (p<0.05). CGRP administration significantly (p<0.05) attenuated the anaerobic changes in the myocardium (decrease in PCr) and macrohemodynamic alterations (increase in CPP, decrease in dP/dt etc.) induced by ET-1.We conclude that CGRP effectively confers hemodynamic and metabolic protection to isolated beating hearts against ET-1-induced myocardial ischemia.
- Electroacupuncture at Acupoints Reverses Plasma Glutamate, Lipid, and LDL/VLDL in an Acute Migraine Rat Model: A (1) H NMR-Based Metabolomic Study. [Journal Article]
- Evid Based Complement Alternat Med 2014.:659268.
Background.The objective of this study was to identify potential biomarkers of electroacupuncture (EA) on relieving acute migraine through metabolomic study. Methods. EA treatments were performed on both acupoints and nonacupoints on the nitroglycerin (NTG)-induced migraine rat model. NMR experiments and multivariate analysis were used for metabolomic analysis.
Results.The number of head-scratching, the main ethology index of migraine rat model, was significantly increased (P < 0.01) after NTG injection. The plasma metabolic profile of model group was distinct from that of the control group. Glutamate was significantly increased (P < 0.01), whereas lipids were significantly decreased (P < 0.01) in model rats. After EA at acupoints, the metabolic profile of model rats was normalized, with decreased glutamate (P < 0.05) and increased lipids (P < 0.01). In contrast, EA at nonacupoints did not restore the metabolic profile, but with six metabolites significantly different from acupoints group. Interestingly, the number of head-scratching and glutamate level were significantly decreased (P < 0.05) after receiving EA at both acupoints and nonacupoints.
Conclusions.EA at acupoints may relieve acute migraine by restoring the plasma metabolic profile and plasma glutamate, while EA at nonacupoints may modestly relieve acute migraine by decreasing plasma glutamate.
- Massage Therapy Restores Peripheral Vascular Function following Exertion. [JOURNAL ARTICLE]
- Arch Phys Med Rehabil 2014 Feb 25.
To determine if lower extremity exercise-induced muscle injury (EMI) reduces vascular endothelial function of the upper extremity and if massage therapy (MT) improves peripheral vascular function after EMI.Randomized, blinded trial with evaluations at 90 minutes, 24 hours, 48 hours, and 72 hours.Clinical research center at an academic medical center and laboratory PARTICIPANTS: Thirty-six sedentary young adults were randomly assigned to one of three groups: 1) EMI + MT (n=15; mean age ± standard error (SE): 26.6±0.3), 2) EMI only (n=10; mean age ± SE: 23.6±0.4), and 3) MT only (n=11; mean age ± SE: 25.5 ± 0.4).Participants were assigned to either EMI only (a single bout of bilateral, eccentric leg-press exercise), MT only (30-minute lower extremity massage using Swedish technique), or EMI + MT.Brachial artery flow-mediated dilation (FMD) was determined by ultrasound at each time point. Nitroglycerin-induced dilation was also assessed (NTG; 0.4 mg).Brachial FMD increased from baseline in the EMI + MT group and the MT only group (7.38±0.18 to 9.02±0.28%, p<0.05 and 7.77±0.25 to 10.20±0.22%, p < 0.05, respectively) at 90 minutes remaining elevated until 72 hrs. In the EMI only group FMD was reduced from baseline at 24 and 48 hrs (7.78±0.14 to 6.75±0.11%, p<0.05 and 6.53±0.11, p<0.05, respectively) returning to baseline after 72 hrs. Dilations to NTG were similar over time.Our results suggest that MT attenuates impairment of upper extremity endothelial function resulting from lower extremity EMI in sedentary young adults.
- Stability of nitroglycerin 110 mcg/mL stored in polypropylene syringes. [Journal Article, Research Support, Non-U.S. Gov't]
- Int J Pharm Compd 2013 Nov-Dec; 17(6):515-9.
Various angiography procedures at Mayo Clinic (Rochester campus) require small bolus doses of injectable nitroglycerin. Commercially acquired containers of injectable nitroglycerin provide excessive amounts of drug for these procedural needs, so syringes were chosen as a container for dispensing of the dose needed. Due to nitroglycerin's known chemical attributes of volatility and sorption to plastic surfaces, careful consideration of the stability needs to be taken into account when storing in a syringe. Since there is a lack of stability information in the literature, we studied the stability of nitroglycerin in polypropylene syringes over 90 days. Methods used for this study consisted of a validated stability-indicating high-performance liquid chromatographic assay, visual appearance, and pH. Samples were stored protected from light at ambient controlled temperature and consisted of nitroglycerin 110 mcg/mL in 5% dextrose injection 10.1 mL in 12 mL Terumo polypropylene syringes. Samples were tested at intervals up to 90 days. Results from the visual portion of the study showed clear, colorless, and particulate-free solutions throughout the 90-day study period. The pH results started at 4.27 +/- 0.13 (day 0) and ranged from 4.19 +/- 0.17 to 4.92 +/- 0.43 throughout the study period. Potency test results revealed a day 0 concentration of 104.242 +/- 0.193 mcg/mL (batch 1) and 122.483 +/- 0.168 mcg/mL (batch 2). Results trended downward with percentage of day 0 concentration of 92.2% +/- 2.4% at day 14 and of 81.4% +/- 4.9% at day 90. Chromatographic profiles of the samples exhibited insignificant changes over the study period. The nitroglycerin peak was spectrally pure based on peak-purity analysis, suggesting that sorption to the polypropylene syringe is one possible reason for the concentration decline over time, but nitroglycerin is a volatile compound and loss through vaporization cannot be ruled out. Nitroglycerin 110 mcg/mL in 5% dextrose injection, packaged in Terumo polypropylene syringes with 10.1 mL aliquots, maintained 90% of syringe potency for 24 days when stored protected from light under controlled ambient conditions.
- Cost-Effectiveness of Ranolazine Added to Standard-of-Care Treatment in Patients With Chronic Stable Angina Pectoris. [JOURNAL ARTICLE]
- Am J Cardiol 2014 Jan 31.
Ranolazine has been shown to decrease angina pectoris frequency and nitroglycerin consumption. We assessed the cost-effectiveness of ranolazine when added to standard-of-care (SoC) antianginals compared with SoC alone in patients with stable coronary disease experiencing ≥3 attacks/week. A Markov model utilizing a societal perspective, a 1-month cycle length, and a 1-year time horizon was developed to estimate costs (2013 US$) and quality-adjusted life years (QALYs) for patients receiving and not receiving ranolazine. Patients entered the model in 1 of the 4 angina frequency health states based upon Seattle Angina Questionnaire angina frequency (SAQAF) scores (100 = no; 61 to 99 = monthly; 31 to 60 = weekly; and 0 to 30 = daily angina) and were allowed to transition between states or to death based upon probabilities derived from the Efficacy of Ranolazine in Chronic Angina and other studies. Patients not responding to ranolazine in month 1 (not improving ≥1 SAQAF health state) were assumed to discontinue ranolazine and behave like SoC patients. Ranolazine patients lived a mean of 0.700 QALYs at a cost of $15,661. Those not receiving ranolazine lived 0.659 QALYs and at a cost of $14,321. The incremental cost-effectiveness ratio (ICER) for the addition of ranolazine was $32,682/QALY. The ICER was most sensitive to ranolazine cost but only exceeded $50,000/QALY when the cost of ranolazine increased >32% above base case. The ICER remained <$50,000/QALY when indirect costs were excluded, and mortality rates were assumed equivalent between SAQAF health states. Monte Carlo simulation found ranolazine cost-effective in 97% of 10,000 iterations at a $50,000/QALY willingness-to-pay threshold. In conclusion, ranolazine added to SoC is cost-effective in patients with weekly or daily angina.
- Relation of mitochondrial oxygen consumption in peripheral blood mononuclear cells to vascular function in type 2 diabetes mellitus. [Journal Article]
- Vasc Med 2014 Feb; 19(1):67-74.
Recent studies have shown mitochondrial dysfunction and increased production of reactive oxygen species in peripheral blood mononuclear cells (PBMCs) and endothelial cells from patients with diabetes mellitus. Mitochondria oxygen consumption is coupled to adenosine triphosphate (ATP) production and also occurs in an uncoupled fashion during formation of reactive oxygen species by components of the electron transport chain and other enzymatic sites. We therefore hypothesized that diabetes would be associated with higher total and uncoupled oxygen consumption in PBMCs that would correlate with endothelial dysfunction. We developed a method to measure oxygen consumption in freshly isolated PBMCs and applied it to 26 patients with type 2 diabetes mellitus and 28 non-diabetic controls. Basal (192±47 vs 161±44 pmoles/min, p=0.01), uncoupled (64±16 vs 53±13 pmoles/min, p=0.007), and maximal (795±87 vs 715±128 pmoles/min, p=0.01) oxygen consumption rates were higher in diabetic patients compared to controls. There were no significant correlations between oxygen consumption rates and endothelium-dependent flow-mediated dilation measured by vascular ultrasound. Non-endothelium-dependent nitroglycerin-mediated dilation was lower in diabetics (10.1±6.6 vs 15.8±4.8%, p=0.03) and correlated with maximal oxygen consumption (r = -0.64, p=0.001). In summary, we found that diabetes mellitus is associated with a pattern of mitochondrial oxygen consumption consistent with higher production of reactive oxygen species. The correlation between oxygen consumption and nitroglycerin-mediated dilation may suggest a link between mitochondrial dysfunction and vascular smooth muscle cell dysfunction that merits further study. Finally, the described method may have utility for the assessment of mitochondrial function in larger scale observational and interventional studies in humans.
- Role of the Lipid Peroxidation Product, 4-Hydroxynonenal, in the Development of Nitrate Tolerance. [JOURNAL ARTICLE]
- Chem Res Toxicol 2014 Feb 27.
Tolerance to nitrates such as nitroglycerin (GTN) is associated with oxidative stress, inactivation of aldehyde dehydrogenase 2 (ALDH2), and decreased GTN-induced cGMP accumulation and vasodilation. We hypothesized that GTN-induced inactivation of ALDH2 results in increased 4-hydroxy-2-nonenal (HNE) adduct formation of key proteins involved in GTN bioactivation, and, consequently, an attenuated vasodilator response to GTN (i.e., tolerance). We used an in vivo GTN tolerance model, a cell culture model of nitrate action, and Aldh2(-/-) mice to assess whether GTN exposure resulted in HNE adduct formation, and whether exogenous HNE affected GTN-induced relaxation and cGMP accumulation. Immunoblot analysis indicated a marked increase in HNE adduct formation in GTN-tolerant porcine kidney epithelial cells (PK1) and in aortae from GTN-tolerant rats and untreated Aldh2(-/-) mice. Preincubation of PK1 cells with HNE resulted in a dose-dependent decrease in GTN-induced cGMP accumulation, and pretreatment of isolated rat aorta with HNE resulted in dose-dependent decreases in the vasodilator response to GTN, thus mimicking GTN-tolerance. Pretreatment of aortae from Aldh2(-/-) mice with 10 μM HNE resulted in a desensitized vasodilator response to GTN. In the in vivo rat tolerance model, changes in HNE adduct formation correlated well with the onset of GTN tolerance and tolerance reversal. Furthermore, coadministration of an HNE scavenger during the tolerance induction protocol completely prevented HNE adduct formation and GTN tolerance but did not prevent the inactivation of ALDH2. The data are consistent with a novel mechanism of GTN tolerance suggesting a primary role of HNE adduct formation in the development of GTN tolerance.
- No evidence of nitrate tolerance caused by nebivolol. [JOURNAL ARTICLE]
- Ther Adv Cardiovasc Dis 2014 Feb 13.
Continuous long-term treatment with nitrates may cause nitrate tolerance. Nebivolol is a highly selective beta1-adrenergic antagonist with additional nitric oxide (NO)-mediated vasodilatory effects. However, there have been no investigations into whether or not the long-term administration of nebivolol might cause nitrate tolerance.We performed a randomized, double-blind, placebo-controlled, cross-over study in 16 healthy men. Subjects received 5 mg nebivolol or placebo once daily for 8 days in random order divided by a drug-free interval of 2 weeks. Forearm blood flow (FBF) was measured by venous occlusion plethysmography 3 h after oral intake of the first and last doses of nebivolol and placebo, respectively. FBF was measured again following the intravenous administration of 4 μg nitroglycerin/kg body weight/min for 5 min.Following 8 days of continuous intake of placebo, nitroglycerin increased FBF by 54% (p < 0.05), whereas nitroglycerin increased FBF by 96% (p < 0.01) following 8 days of continuous intake of nebivolol, and the increase after 8 days of nebivolol was significantly (p < 0.05) more pronounced than after 8 days of placebo.These findings indicate no evidence of nitrate tolerance caused by long-term administration of nebivolol. On the contrary, long-term intake of nebivolol increases rather than decreases the NO-mediated vasodilating effects.
- Augmentation Pressure Is Influenced by Ventricular Contractility/Relaxation Dynamics: Novel Mechanism of Reduction of Pulse Pressure by Nitrates. [JOURNAL ARTICLE]
- Hypertension 2014 Feb 10.
Augmentation pressure (AP), the increment in aortic pressure above its first systolic shoulder, is thought to be determined mainly by pressure wave reflection but could be influenced by ventricular ejection characteristics. We sought to determine the mechanism by which AP is selectively reduced by nitroglycerin (NTG). Simultaneous measurements of aortic pressure and flow were made at the time of cardiac catheterization in 30 subjects (11 women; age, 61±13 years [mean±SD]) to perform wave intensity analysis and calculate forward and backward components of AP generated by the ventricle and arterial tree, respectively. Measurements were made at baseline and after NTG given systemically (800 μg sublingually, n=20) and locally by intracoronary infusion (1 μg/min; n=10). Systemic NTG had no significant effect on first shoulder pressure but reduced augmentation (and central pulse pressure) by 12.8±3.1 mm Hg (P<0.0001). This resulted from a reduction in forward and backward wave components of AP by 7.0±2.4 and 5.8±1.3 mm Hg, respectively (each P<0.02). NTG had no significant effect on the ratio of amplitudes of either backward/forward waves or backward/forward compression wave energies, suggesting that effects on the backward wave were largely secondary to those on the forward wave. Time to the forward expansion wave was reduced (P<0.05). Intracoronary NTG decreased AP by 8.3±3.6 mm Hg (P<0.05) with no significant effect on the backward wave. NTG reduces AP and central pulse pressure by a mechanism that is, at least in part, independent of arterial reflections and relates to ventricular contraction/relaxation dynamics with enhanced myocardial relaxation.