The purpose of this study was to assess the influence of genetic background and sex on nitric oxide (NO)‐mediated vasomotor function in arteries from different vascular territories. Vasomotor ...function was assessed in thoracic aorta, abdominal aorta, carotid arteries, and femoral arteries from the following mouse strains: SJL/J, DBA/2J, NZW/LacJ, and C57BL/6J. Contractile responses were assessed using the α1‐adrenergic receptor agonist phenylephrine (PE, 10−9–10−5 M). Vasorelaxation responses were assessed by examining relaxation to an endothelium‐dependent vasodilator acetylcholine (ACh, 10−9–10−5 M) and an endothelium‐independent vasodilator sodium nitroprusside (SNP, 10−9–10−5 M). To evaluate the role of NO, relaxation responses to ACh and SNP were assessed in the absence or presence of a nitric oxide synthase inhibitor (N omega‐nitro‐l‐arginine methyl ester hydrochloride: 10−4 M). Vasomotor responses to ACh and PE varied across strains and among the arteries tested with some strains exhibiting artery‐specific impairment. Results indicated some concentration–response heterogeneity in response to ACh and SNP between vessels from females and males, but no significant differences in responses to PE. Collectively, these findings indicate that vasomotor responses vary by genetic background, sex, and artery type.
Insufficient stress response and elevated oxidative stress can contribute to skeletal muscle atrophy during mechanical unloading (e.g., spaceflight and bedrest). Perturbations in heat shock proteins ...(e.g., HSP70), antioxidant enzymes, and sarcolemmal neuronal nitric oxidase synthase (nNOS) have been linked to unloading-induced atrophy. We recently discovered that the sarcolemmal NADPH oxidase-2 complex (Nox2) is elevated during unloading, downstream of angiotensin II receptor 1, and concomitant with atrophy. Here, we hypothesized that peptidyl inhibition of Nox2 would attenuate disruption of HSP70, MnSOD, and sarcolemmal nNOS during unloading, and thus muscle fiber atrophy. F344 rats were divided into control (CON), hindlimb unloaded (HU), and hindlimb unloaded +7.5 mg/kg/day gp91ds-tat (HUG) groups. Unloading-induced elevation of the Nox2 subunit p67phox-positive staining was mitigated by gp91ds-tat. HSP70 protein abundance was significantly lower in HU muscles, but not HUG. MnSOD decreased with unloading; however, MnSOD was not rescued by gp91ds-tat. In contrast, Nox2 inhibition protected against unloading suppression of the antioxidant transcription factor Nrf2. nNOS bioactivity was reduced by HU, an effect abrogated by Nox2 inhibition. Unloading-induced soleus fiber atrophy was significantly attenuated by gp91ds-tat. These data establish a causal role for Nox2 in unloading-induced muscle atrophy, linked to preservation of HSP70, Nrf2, and sarcolemmal nNOS.
Skeletal muscle is a highly adaptable tissue capable of remodeling when dynamic stress is altered, including changes in mechanical loading and stretch. When muscle is subjected to an unloaded state ...(e.g., bedrest, immobilization, spaceflight) the resulting loss of muscle cross sectional area (CSA) impairs force production. In addition, muscle fiber-type shifts from slow to fast-twitch fibers. Unloading also results in a downregulation of heat shock proteins (e.g., HSP70) and anabolic signaling, which further exacerbate these morphological changes. Our lab recently showed reactive oxygen species (ROS) are causal in unloading-induced alterations in Akt and FoxO3a phosphorylation, muscle fiber atrophy, and fiber-type shift. Nutritional supplements such as fish oil and curcumin enhance anabolic signaling, glutathione levels, and heat shock proteins. We hypothesized that fish oil, rich in omega-3-fatty acids, combined with the polyphenol curcumin would enhance stress protective proteins and anabolic signaling in the rat soleus muscle, concomitant with synergistic protection of morphology. C57BL/6 mice were assigned to 3 groups (n = 6/group): ambulatory controls (CON), hindlimb unloading (HU), and hindlimb unloading with 5% fish oil, 1% curcumin in diet (FOC). FOC treatments began 10 days prior to HU and tissues were harvested following 7 days of HU. FOC mitigated the unloading induced decrease in CSA. FOC also enhanced abundance of HSP70 and anabolic signaling (Akt phosphorylation, p70S6K phosphorylation), while reducing Nox2, a source of oxidative stress. Therefore, we concluded that the combination of fish oil and curcumin prevents skeletal muscle atrophy due to a boost of heat shock proteins and anabolic signaling in an unloaded state.
Aging is associated with impaired vascular function characterized in part by attenuated vasorelaxation to acetylcholine (ACh) and sodium nitroprusside (SNP). Due to structural and functional ...differences between conduit and resistance arteries, the effect of aging on vasorelaxation responses may vary along the arterial tree. Our purpose was to determine age‐related differences in vasorelaxation responses in large and small arteries. Responses to the endothelium‐dependent vasodilator acetylcholine (ACh) and the endothelium‐independent vasodilator sodium nitroprusside (SNP) were assessed in abdominal aorta (AA), iliac arteries (IA), femoral arteries (FA), and gastrocnemius feed arteries (GFA) from young and old male rats. ACh‐mediated vasorelaxation was significantly impaired in old AA and IA. SNP‐mediated vasorelaxation was impaired in old AA. To investigate a potential mechanism for impaired relaxation responses in AA and IA, we assessed eNOS protein content and interactions with caveolin‐1 (Cav‐1), and calmodulin (CaM) via immunoprecipitation and immunoblot analysis. We found no age differences in eNOS content or interactions with Cav1 and CaM. Combined data from all rats revealed that eNOS content was higher in IA compared to AA and FA (p < .001), and was higher in GFA than AA (p < .05). Cav1:eNOS interaction was greater in FA than in AA and IA (p < .01), and in GFA compared to IA (p < .05). No differences in CaM:eNOS were detected. In conclusion, age‐related impairment of vasorelaxation responses occurred in the large conduit, but not small conduit or resistance arteries. These detrimental effects of age were not associated with changes in eNOS or its interactions with Cav‐1 or CaM.
Our purpose was to determine age‐related differences in vasorelaxation responses in large and small arteries. Results revealed that age‐related impairment of vasorelaxation responses occurred in the large conduit, but not small conduit or resistance arteries. These detrimental effects of age were not associated with changes in eNOS or its interactions with Cav‐1 or CaM.
Introduction
Endothelial dysfunction is associated with a host of disease states including cardiovascular disease, diabetes, chronic kidney disease, and atherosclerosis. Previous research by our ...laboratory has shown that vasomotor function, and more specifically endothelium‐dependent vasorelaxation responses, differ across large arteries from mice with distinct genetic backgrounds. However, it is unclear how much of the observed variation in endothelium‐dependent vasorelaxation is due to nitric oxide (NO) mediated pathways.
Objective
The purpose of this study was to test the hypothesis that strain‐dependent vasorelaxation differences were primarily the result of differences in reliance on NO‐mediated pathways.
Methods
Vasomotor function was assessed in thoracic aorta, abdominal aorta, carotid arteries, and femoral arteries from four inbred strains (SJL/J (SJL), DBA/2J (DBA), NZW/LacJ (NZW) and C57BL/6J (B6)) of mice. Strains were chosen based on previously documented vasomotor variation and susceptibility to clinically significant pathologies. Arteries were dissected, cut into 2mm segments, and mounted in a wire myograph system. Arterial segments were stretched to a resting tension equivalent to a pressure of 90mmHg for all strains based on a passive stretch and relaxation tension‐force assessment. Increasing concentrations of the endothelium‐dependent vasodilator acetylcholine (ACh, 1x10‐9 – 1x10‐5M) and endothelium‐independent vasodilator sodium nitroprusside (SNP, 1x10‐9 – 1x10‐5M) were used to assess vasorelaxation responses. To assess reliance on NO, vasorelaxation responses to Ach and SNP were assessed in the presence of a nitric oxide synthase inhibitor (NOS). One arterial segment from each group was treated with the NOS inhibitor N omega‐Nitro‐L‐arginine methyl ester hydrochloride (L‐NAME: 10x4 M) for thirty minutes.
Results
Two way ANOVA revealed a significant main effect of strain in vasorelaxation responses to ACh for all arteries tested (P <.0001) and no significant differences in response to SNP. Maximal relaxation responses to ACh were significantly inhibited in all arterial segments treated with L‐NAME, while no differences were detected for L‐NAME treated vessels in response to SNP. These findings indicate that large arteries have a strong dependence on NO‐mediated, endothelium‐dependent pathways to maintain vascular regulation. Furthermore, strain‐dependent vasorelaxation differences were abolished in the presence of L‐NAME indicating that strain differences were NO‐dependent.
Conclusion
These findings indicate a strong influence of genetic background on endothelial function and suggest that these differences are primarily due to strain related reliance on NO for endothelium‐dependent vasodilation.
Abstract only The endothelium is crucial for its role in maintaining vascular integrity and protecting against cardiovascular disease. Endothelial dysfunction is associated with a host of disease ...states including cardiovascular disease, diabetes, chronic kidney disease, and atherosclerosis. However, it is unclear whether endothelial function or dysfunction varies throughout the vasculature. In addition, accumulating evidence suggests that endothelial function, and more generally vasomotor function, is genetically regulated. The purpose of this study was to determine the influence of genetic background on vasomotor function in blood vessels of differing size. Vasomotor performance was measured in aorta (thoracic (TA), and abdominal (AA)) and conduit arteries (carotid artery (CA) and femoral artery (FA)) from four inbred strains (SJL/J (SJL), DBA/2J (DBA), NZW/LacJ (NZW) and C57BL/6J (B6)) of mice. Arteries were dissected, cut into 2 mm segments, and mounted in a wire myograph system. Increasing concentrations of phenylephrine (PE, 1×10 −9 – 1×10 −5 M) were used to measure contractile responses, while increasing concentrations of the endothelium‐dependent vasodilator acetylcholine (ACh, 1×10 −9 – 1×10 −5 M) and endothelium‐independent vasodilator sodium nitroprusside (SNP, 1×10 −9 – 1×10 −5 M) were used to assess relaxation responses. Two way ANOVA revealed a significant main effect of strain in response to PE for AA (P = .0032) and CA (P = .0098). Post hoc analysis for max contractile response showed impaired vasoconstriction in NZW AA compared to B6 (P = .0004). In response to ACh, a significant main effect of strain was found for all vessels (TA: P = <.0001, AA: P = .0156, CA: P = .0069, FA: P = <.0001). Post hoc analysis showed that TA max vasorelaxation was impaired for all strains (NZW: P = < .0001, DBA: P = .0140, SJL: P = < .0001) and that NZW FA were impaired when compared to B6 ( P = .0015). A significant main effect of strain in response to SNP was found in TA (P = .0011), AA (P = .0086), and CA (P = < .0001). Relaxation responses to SNP were not significantly different between strains. These findings indicate a strong influence of genetic background on endothelial function and could be important in understanding the implications that genetics have on vascular response to vasoactive agents. Support or Funding Information This work was supported by a Texas A&M Triads for Transformation grant (MPM), a Texas A&M Merit Fellowship (DH), a Texas A&M College of Education Strategic Research Award (SYS), and J.L. Huffines Institute of Sports Medicine and Human Performance (SYS).
The endothelium is critical for maintaining vascular integrity and protecting against cardiovascular disease. Endothelial dysfunction is associated with a host of disease states including ...cardiovascular disease, diabetes, chronic kidney disease, and Alzheimer's disease. However, it is unclear whether endothelial function or dysfunction varies throughout the vasculature. In addition, accumulating evidence suggests that endothelial function, and more generally vasomotor function, is genetically regulated. The purpose of this study was to determine the influence of genetic background on vasomotor function in blood vessels of differing size. Vasomotor function was measured in aorta (thoracic (TA), and abdominal (AA)) and conduit arteries (carotid artery (CA) and femoral artery (FA)) from two inbred strains (NZW/LacJ (NZW) and C57BL/6J (B6)) of mice. Arteries were dissected, cut into 2 mm segments, and mounted in a wire myograph system. Increasing concentrations of phenylephrine (PE, 1×10−9 – 1×10−5M) were used to measure contractile responses, while increasing concentrations of the endothelium‐dependent vasodilator acetylcholine (ACh, 1×10−9 – 1×10−5M) and endothelium‐independent vasodilator sodium nitroprusside (SNP, 1×10−9 – 1×10−5M) were used to assess relaxation responses. Contractile responses to PE were not significantly different between strains across all vessels. Endothelium‐dependent relaxation to ACh was significantly impaired in TA (P = .0001), AA (P = .0019), and FA (P = .0002) from NZW as compared to B6, while CA relaxation responses were not statistically different between groups. Sensitivity to ACh as determined by IC50 was impaired in NZW TA (P = .0006), AA (P = .0005), CA (P = .001), and FA (P = .0003). Relaxation responses to the endothelium‐independent vasodilator SNP were not statistically different in the AA, CA and FA, while TA relaxation to SNP was statistically lower in B6 TA compared to NZW (P = .02). Sensitivity to SNP was not statistically different between groups for TA, CA, and FA but NZW AA showed a greater sensitivity to SNP than did B6 (P = .0304). These findings indicate a strong influence of genetic background on vasomotor function and could be important in understanding the implications that genetics have on vascular response to vasoactive agents.
Support or Funding Information
This work was supported by a Texas A&M Triads for Transformation grant (Michael Massett, Christopher Woodman), a Texas A&M Merit Fellowship (Dylan Holly), and a Texas A&M College of Education Strategic Research Award (Song Yi Shin).
This is from the Experimental Biology 2019 Meeting. There is no full text article associated with this published in The FASEB Journal.
Aging is associated with impaired vasomotor function. However, due to structural and functional differences between conduit and elastic arteries, the effect of aging on vasomotor function might vary ...throughout the vascular tree. Thus, the purpose of this study was to determine if there are any aging‐related differences in endothelial function between different sized vessels throughout the vascular tree. Large (abdominal aorta (AA), iliac artery (IA)) and small (femoral artery (FA), gastrocnemius feed artery (GFA)) arteries were isolated from young (4 months) and old (24 months) male Fischer 344 rats. Vessels were cut into 2 mm segments and mounted in a wire myograph. Cumulative concentrations of phenylephrine (PE, 1 × 10−9 M – 1 × 10−5 M) were used to assess contractile responses. To assess relaxation responses, vessels were treated with increasing concentrations of the endothelium‐dependent vasodilator acetylcholine (ACh) and the endothelium‐independent vasodilator sodium nitroprusside (SNP) (1 × 10−9 M – 1 × 10−5 M). Contractile responses to PE were significantly greater in all vessels from young rats compared with old rats. Aging‐related differences in the relaxation responses to ACh varied among the vessels. Relaxation responses to ACh were significantly impaired in AA from old rats compared to young rats (P = 0.0008). ACh‐induced relaxation in IA tended to be reduced in vessels from old rats compared with young (P = 0.051). In contrast, there were no differences for responses in FA (P = 0.10) and GFA (P = 0.80). For the endothelium independent dilator SNP, only AA showed significant differences in relaxation responses between arteries from young and old rats. Relaxation responses to low concentrations of SNP (10−9 M – 10−7 M) were blunted in AA from old rats, but maximal relaxation was not different between young and old. To investigate a potential mechanism for reduced endothelium dependent relaxation in AA and IA, protein content of eNOS, caveolin‐1 (CaV‐1), calmodulin (CaM) and their interactions (CaV‐1:eNOS and CaM:eNOS) were assessed by immunoblot analysis. CaV‐1 is a negative regulator of eNOS activity, whereas CaM is a positive regulator. In AA, both CaV‐1:eNOS and CaM:eNOS were reduced in vessels from old rats compared with young rats. CaV‐1:eNOS was increased in IA from old rats compared with young rats. Collectively, these results indicate that age‐related impaired responses to ACh occur in large but not smaller arteries. The impaired responses were associated with changes in protein levels of CaV‐1 and CaM. These results suggest that non‐uniform changes in protein:protein interactions might contribute to heterogeneous changes in endothelial function with aging.
Support or Funding Information
The authors recognize the support of the National Institute on Aging for providing the animals used in this study. This work was supported by AHA (4150031) and Sydney and J.L Huffines Institute for Sports Medicine and Human Performance Grants to CW, and Texas A&M College of Education Strategic Research Award to SS.
This is from the Experimental Biology 2019 Meeting. There is no full text article associated with this published in The FASEB Journal.
New Findings
What is the central question of this study?
Translocation of nNOSμ initiates catabolic signalling via FoxO3a and skeletal muscle atrophy during mechanical unloading. Recent evidence ...suggests that unloading‐induced muscle atrophy and FoxO3a activation are redox sensitive. Will a mimetic of superoxide dismutase and catalase (i.e. Eukarion‐134) also mitigate suppression of the Akt–mTOR pathway?
What is the main finding and its importance?
Eukarion‐134 rescued Akt–mTOR signalling and sarcolemmal nNOSμ, which were linked to protection against the unloading phenotype, muscle fibre atrophy and partial fibre‐type shift from slow to fast twitch. The loss of nNOSμ from the sarcolemma appears crucial to Akt phosphorylation and is redox sensitive, although the mechanisms remain unresolved.
Mechanical unloading stimulates rapid changes in skeletal muscle morphology, characterized by atrophy of muscle fibre cross‐sectional area and a partial fibre‐type shift from slow to fast twitch. Recent studies revealed that oxidative stress contributes to activation of forkhead box O3a (FoxO3a), proteolytic signalling and unloading‐induced muscle atrophy via translocation of the μ‐splice variant of neuronal nitric oxide synthase (nNOSμ) and activation of FoxO3a. There is limited understanding of the role of reactive oxygen species in the Akt–mammalian target of rapamycin (mTOR) pathway signalling during unloading. We hypothesized that Eukarion‐134 (EUK‐134), a mimetic of the antioxidant enzymes superoxide dismutase and catalase, would protect Akt–mTOR signalling in the unloaded rat soleus. Male Fischer 344 rats were separated into the following three study groups: ambulatory control (n = 11); 7 days of hindlimb unloading + saline injections (HU, n = 11); or 7 days of HU + EUK‐134; (HU + EUK‐134, n = 9). EUK‐134 mitigated unloading‐induced dephosphorylation of Akt, as well as FoxO3a, in the soleus. Phosphorylation of mTOR in the EUK‐treated HU rats was not different from that in control animals. However, EUK‐134 did not significantly rescue p70S6K phosphorylation. EUK‐134 attenuated translocation of nNOSμ from the membrane to the cytosol, reduced nitration of tyrosine residues and suppressed upregulation of caveolin‐3 and dysferlin. EUK‐134 ameliorated HU‐induced remodelling, atrophy of muscle fibres and the 12% increase in type II myosin heavy chain‐positive fibres. Attenuation of the unloaded muscle phenotype was associated with decreased reactive oxygen species, as assessed by ethidium‐positive nuclei. We conclude that oxidative stress affects Akt–mTOR signalling in unloaded skeletal muscle. Direct linkage of abrogation of nNOSμ translocation with Akt–mTOR signalling during unloading is the subject of future investigation.
Background. Basic numeracy skills are necessary before patients can understand the risks of medical treatments. Previous research has used objective measures, similar to mathematics tests, to ...evaluate numeracy. Objectives. To design a subjective measure (i.e., self-assessment) of quantitative ability that distinguishes low- and high-numerate individuals yet is less aversive, quicker to administer, and more useable for telephone and Internet surveys than existing numeracy measures. Research Design. Paper-and-pencil questionnaires. Subjects. The general public (N = 703) surveyed at 2 hospitals. Measures. Forty-nine subjective numeracy questions were compared to measures of objective numeracy. Results. An 8-item measure, the Subjective Numeracy Scale (SNS), was developed through several rounds of testing. Four items measure people's beliefs about their skill in performing various mathematical operations, and 4 measure people's preferences regarding the presentation of numerical information. The SNS was significantly correlated with Lipkus and others' objective numeracy scale (correlations: 0.63—0.68) yet was completed in less time (24 s/item v. 31 s/item, P < 0.05) and was perceived as less stressful (1.62 v. 2.69, P < 0.01) and less frustrating (1.92 v. 2.88, P < 0.01). Fifty percent of participants who completed the SNS volunteered to participate in another study, whereas only 8% of those who completed the Lipkus and others scale similarly volunteered (odds ratio = 11.00, 95% confidence interval = 2.14—56.65). Conclusions. The SNS correlates well with mathematical test measures of objective numeracy but can be administered in less time and with less burden. In addition, it is much more likely to leave participants willing to participate in additional research and shows much lower rates of missing or incomplete data.
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