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Rizzoto G, Kastelic JP. A new paradigm regarding testicular thermoregulation in ruminants? Theriogenology 2019; 147:166-175. [PMID: 31785861 DOI: 10.1016/j.theriogenology.2019.11.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 11/16/2019] [Accepted: 11/17/2019] [Indexed: 02/05/2023]
Abstract
Increased testicular temperature reduces percentages of morphologically normal and motile sperm and fertility. Specific sperm defects appear at consistent intervals after testicular hyperthermia, with degree and duration of changes related to intensity and duration of the thermal insult. Regarding pathogenesis of testicular hyperthermia on sperm quality and fertility, there is a long-standing paradigm that: 1) testes operate near hypoxia; 2) blood flow to the testes does not increase in response to increased testicular temperature; and 3) an ensuing hypoxia is the underlying cause of heat-induced changes in sperm morphology and function. There are very limited experimental data to support this paradigm, but we have data that refute it. In 2 × 3 factorial studies, mice and rams were exposed to two testicular temperatures (normal and increased) and three concentrations of O2 in inspired air (hyperoxia, normoxia and hypoxia). As expected, increased testicular temperature had deleterious effects on sperm motility and morphology; however, hyperoxia did not prevent these changes nor did hypoxia replicate them. In two follow-up experiments, anesthetized rams were sequentially exposed to: 1) three O2 concentrations (100, 21 and 13% O2); or 2) three testicular temperatures (33, 37 and 40 °C). As O2, decreased, testis maintained O2 delivery and uptake by increasing testicular blood flow and O2 extraction, with no indication of anaerobic metabolism. Furthermore, as testicular temperature increased, testicular metabolic rate nearly doubled, but increased blood flow and O2 extraction prevented testicular hypoxia and anaerobic metabolism. In conclusion, our data, in combination with other reports, challenged the paradigm that testicular hyperthermia fails to increase testicular blood flow and the ensuing hypoxia disrupts spermatogenesis.
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Affiliation(s)
- G Rizzoto
- Faculty of Veterinary Medicine, Department of Production Animal Health, University of Calgary, 3280 Hospital Drive, Calgary, AB, Canada, T2N 4Z6
| | - J P Kastelic
- Faculty of Veterinary Medicine, Department of Production Animal Health, University of Calgary, 3280 Hospital Drive, Calgary, AB, Canada, T2N 4Z6.
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SKA-31, an activator of endothelial Ca 2+-activated K + channels evokes robust vasodilation in rat mesenteric arteries. Eur J Pharmacol 2018; 831:60-67. [PMID: 29753043 DOI: 10.1016/j.ejphar.2018.05.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 05/04/2018] [Accepted: 05/08/2018] [Indexed: 12/17/2022]
Abstract
It is now well recognized that endothelial KCa2.3 and KCa3.1 channel activities contribute to dilation of resistance arteries via endothelium-mediated hyperpolarization and vascular smooth muscle relaxation. In this study, we have investigated the functional effect of the KCa channel activator SKA-31 in third order rat mesenteric arteries using arterial pressure myography. Isolated arteries were cannulated, pressurized intraluminally to 70 mmHg at 36 °C and then constricted with 1 μM phenylephrine. Acute bath exposure to SKA-31 evoked a robust and reversible inhibition of developed tone (IC50 = 0.22 μM). The vasodilatory effects of SKA-31 and acetylcholine were blunted in the presence of KCa2.3 and KCa3.1 channel antagonists, and were largely prevented following endothelial denudation. Western blot and q-PCR analyses of isolated mesenteric arteries revealed KCa2.3 and KCa3.1 channel expression at the protein and mRNA levels, respectively. Penitrem-A, an inhibitor of KCa1.1 channels, decreased vasodilatory responses to acetylcholine, sodium nitroprusside and NS-1619, but had little effect on SKA-31. Similarly, bath exposure to the eNOS inhibitor L-NAME did not alter SKA-31 and acetylcholine-mediated vasodilation. Collectively, these data highlight the major cellular mechanisms by which the endothelial KCa channel activator SKA-31 inhibits agonist-evoked vasoconstriction in rat small mesenteric arteries.
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Coleman HA, Tare M, Parkington HC. Nonlinear effects of potassium channel blockers on endothelium-dependent hyperpolarization. Acta Physiol (Oxf) 2017; 219:324-334. [PMID: 27639255 DOI: 10.1111/apha.12805] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 02/12/2016] [Accepted: 09/13/2016] [Indexed: 12/17/2022]
Abstract
In a number of published studies on endothelium-dependent hyperpolarization and relaxation, the results of the effects of K+ blockers have been difficult to interpret. When the effects of two blockers have been studied, often either blocker by itself had little effect, whereas the two blockers combined tended to abolish the responses. Explanations suggested in the literature include an unusual pharmacology of the K+ channels, and possible blocker binding interactions. In contrast, when we applied the same blockers to segments of small blood vessels under voltage clamp, the blockers reduced the endothelium-dependent K+ current in a linearly additive manner. Resolution of these contrasting results is important as endothelium-derived hyperpolarization (EDH) makes its greatest contribution to vasorelaxation in arterioles and small resistance arteries, where it can exert a significant role in tissue perfusion and blood pressure regulation. Furthermore, EDH is impaired in various diseases. Here, we consider why the voltage-clamp results differ from earlier free-running membrane potential and contractility studies. We fitted voltage-clamp-derived current-voltage relationships with mathematical functions and considered theoretically the effects of partial and total block of endothelium-derived K+ -currents on the membrane potential of small blood vessels. When the K+ -conductance was partially reduced, equivalent to applying a single blocker, the effect on EDH was small. Total block of the endothelium-dependent K+ conductance abolished the hyperpolarization, in agreement with various published studies. We conclude that nonlinear summation of the hyperpolarizing response evoked by endothelial stimulation can explain the variable effectiveness of individual K+ channel blockers on endothelium-dependent hyperpolarization and resulting relaxation.
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Affiliation(s)
- H. A. Coleman
- Department of Physiology; Biomedicine Discovery Institute; Cardiovascular Disease Program; Monash University; Clayton Vic. Australia
| | - M. Tare
- Department of Physiology; Biomedicine Discovery Institute; Cardiovascular Disease Program; Monash University; Clayton Vic. Australia
| | - H. C. Parkington
- Department of Physiology; Biomedicine Discovery Institute; Cardiovascular Disease Program; Monash University; Clayton Vic. Australia
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Abstract
Vascular endothelial cells play a major role in maintaining cardiovascular homeostasis. Impairment of physiological properties of the endothelium, such as the promotion of vasodilation and anti-aggregation, leads to a condition called endothelial dysfunction. Endothelial dysfunction is an important early event in the pathogenesis of atherosclerosis and has been shown to have prognostic value in predicting vascular events including stroke and myocardial infarction.Endothelial-dependent vasodilation is one of the most widely used methods for assessment of endothelial function in rodents. It includes pharmacological stimulation (for example by acetylcholine) of endothelial release of NO and other vasoactive compounds in comparison with vascular response to endothelium-independent dilators such as sodium nitroprusside. However, usually this technique is performed in anesthetized animals. Here we describe a method which allows evaluation of endothelial dysfunction in conscious, freely moving mice and rats.
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García-Pedraza JÁ, García M, Martín ML, Morán A. 5-HT1D receptor inhibits renal sympathetic neurotransmission by nitric oxide pathway in anesthetized rats. Vascul Pharmacol 2015; 72:172-80. [DOI: 10.1016/j.vph.2015.05.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 05/05/2015] [Accepted: 05/09/2015] [Indexed: 10/23/2022]
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García-Pedraza JÁ, García M, Martín ML, Morán A. Pharmacological evidence that 5-HT1Dactivation induces renal vasodilation by NO pathway in rats. Clin Exp Pharmacol Physiol 2015; 42:640-7. [DOI: 10.1111/1440-1681.12397] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 02/18/2015] [Accepted: 03/19/2015] [Indexed: 11/29/2022]
Affiliation(s)
- José-Ángel García-Pedraza
- Laboratory of Pharmacology; Department of Physiology and Pharmacology; Faculty of Pharmacy; University of Salamanca; Salamanca Spain
| | - Mónica García
- Laboratory of Pharmacology; Department of Physiology and Pharmacology; Faculty of Pharmacy; University of Salamanca; Salamanca Spain
| | - María-Luisa Martín
- Laboratory of Pharmacology; Department of Physiology and Pharmacology; Faculty of Pharmacy; University of Salamanca; Salamanca Spain
| | - Asunción Morán
- Laboratory of Pharmacology; Department of Physiology and Pharmacology; Faculty of Pharmacy; University of Salamanca; Salamanca Spain
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García-Pedraza JÁ, García M, Martín ML, San Román L, Morán A. The role of endothelium-derived hyperpolarizing factor and cyclooxygenase pathways in the inhibitory serotonergic response to the pressor effect elicited by sympathetic stimulation in chronic sarpogrelate treated rats. Eur J Pharmacol 2014; 731:80-7. [DOI: 10.1016/j.ejphar.2014.02.043] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 02/14/2014] [Accepted: 02/25/2014] [Indexed: 10/25/2022]
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Durand MJ, Gutterman DD. Diversity in mechanisms of endothelium-dependent vasodilation in health and disease. Microcirculation 2013; 20:239-47. [PMID: 23311975 DOI: 10.1111/micc.12040] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Accepted: 01/07/2013] [Indexed: 12/20/2022]
Abstract
Small arterioles (40-150 μm) contribute to the majority of vascular resistance within organs and tissues. Under resting conditions, the basal tone of these vessels is determined by a delicate balance between vasodilator and vasoconstrictor influences. Cardiovascular homeostasis and regional tissue perfusion is largely a function of the ability of these small blood vessels to constrict or dilate in response to the changing metabolic demands of specific tissues. The endothelial cell layer of these microvessels is a key modulator of vasodilation through the synthesis and release of vasoactive substances. Beyond their vasomotor properties, these compounds importantly modulate vascular cell proliferation, inflammation, and thrombosis. Thus, the balance between local regulation of vascular tone and vascular pathophysiology can vary depending upon which factors are released from the endothelium. This review will focus on the dynamic nature of the endothelial released dilator factors depending on species, anatomic site, and presence of disease, with a focus on the human coronary microcirculation. Knowledge how endothelial signaling changes with disease may provide insights into the early stages of developing vascular inflammation and atherosclerosis, or related vascular pathologies.
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Affiliation(s)
- Matthew J Durand
- Department of Medicine, Cardiology Division, and Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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Marenzana M, Arnett TR. The Key Role of the Blood Supply to Bone. Bone Res 2013; 1:203-15. [PMID: 26273504 DOI: 10.4248/br201303001] [Citation(s) in RCA: 201] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Accepted: 07/22/2013] [Indexed: 12/16/2022] Open
Abstract
The importance of the vascular supply for bone is well-known to orthopaedists but is still rather overlooked within the wider field of skeletal research. Blood supplies oxygen, nutrients and regulatory factors to tissues, as well as removing metabolic waste products such as carbon dioxide and acid. Bone receives up to about 10% of cardiac output, and this blood supply permits a much higher degree of cellularity, remodelling and repair than is possible in cartilage, which is avascular. The blood supply to bone is delivered to the endosteal cavity by nutrient arteries, then flows through marrow sinusoids before exiting via numerous small vessels that ramify through the cortex. The marrow cavity affords a range of vascular niches that are thought to regulate the growth and differentiation of hematopoietic and stromal cells, in part via gradients of oxygen tension. The quality of vascular supply to bone tends to decline with age and may be compromised in common pathological settings, including diabetes, anaemias, chronic airway diseases and immobility, as well as by tumours. Reductions in vascular supply are associated with bone loss. This may be due in part to the direct effects of hypoxia, which blocks osteoblast function and bone formation but causes reciprocal increases in osteoclastogenesis and bone resorption. Common regulatory factors such as parathyroid hormone or nitrates, both of which are potent vasodilators, might exert their osteogenic effects on bone via the vasculature. These observations suggest that the bone vasculature will be a fruitful area for future research.
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Affiliation(s)
- Massimo Marenzana
- Department of Bioengineering, Imperial College London and Kennedy Institute of Rheumatology, University of Oxford , UK
| | - Timothy R Arnett
- Department of Cell and Developmental Biology, University College London , UK
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Kemi OJ, Haram PM, Høydal MA, Wisløff U, Ellingsen Ø. Exercise training and losartan improve endothelial function in heart failure rats by different mechanisms. SCAND CARDIOVASC J 2013. [PMID: 23205578 DOI: 10.3109/14017431.2012.754935] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVES To investigate the mechanisms of losartan- and exercise training-induced improvements on endothelial dysfunction in heart failure. DESIGN Sprague-Dawley rats subjected to left coronary artery ligation inducing myocardial infarction and heart failure were randomized to losartan treatment, high-intensity exercise training, or both. RESULTS Losartan, but not exercise training, reduced the heart failure-associated elevation in left ventricular end-diastolic pressure (26 ± 2 mmHg vs. 19 ± 1 mmHg after losartan). In contrast, both exercise training and losartan improved exercise capacity, by 40% and 20%, respectively; no additional effects were observed when exercise training and losartan were combined. Aortic segments were mounted on a force transducer to determine vasorelaxation. Heart failure impaired endothelium-dependent vasorelaxation, observed as a 1.9-fold reduced response to acetylcholine (EC₅₀). Exercise and losartan improved acetylcholine-mediated vasorelaxation to the same extent, but by different mechanisms. Exercise training upregulated the nitric oxide pathway, whereas losartan upregulated a non-nitric oxide or -prostacyclin pathway; possibly involving the endothelium-dependent hyperpolarizing factor. CONCLUSIONS Both losartan and exercise training reversed endothelial dysfunction in heart failure; exercise training via nitric oxide-dependent vasorelaxation, and losartan via an unknown mechanism that may involve endothelium-dependent hyperpolarizing factor. Thus, the combined treatment activated an additional nitric oxide- independent mechanism that contributed to reduce endothelial dysfunction.
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Affiliation(s)
- Ole Johan Kemi
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK.
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Lu Q, Yao Y, Yao Y, Liu S, Huang Y, Lu S, Bai Y, Zhou B, Xu Y, Li L, Wang N, Wang L, Zhang J, Cheng X, Qin G, Ma W, Xu C, Tu X, Wang Q. Angiogenic factor AGGF1 promotes therapeutic angiogenesis in a mouse limb ischemia model. PLoS One 2012; 7:e46998. [PMID: 23110058 PMCID: PMC3479102 DOI: 10.1371/journal.pone.0046998] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Accepted: 09/11/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Peripheral arterial disease (PAD) is a common disease accounting for about 12% of the adult population, and causes significant morbidity and mortality. Therapeutic angiogenesis using angiogenic factors has been considered to be a potential treatment option for PAD patients. In this study, we assessed the potential of a new angiogenic factor AGGF1 for therapeutic angiogenesis in a critical limb ischemia model in mice for PAD. METHODS AND RESULTS We generated a unilateral hindlimb ischemia model in mice by ligation of the right common iliac artery and femoral artery. Ischemic mice with intrasmuscular administration of DNA for an expression plasmid for human AGGF1 (AGGF1 group) resulted in increased expression of both AGGF1 mRNA and protein after the administration compared with control mice with injection of the empty vector (control group). Color PW Doppler echocardiography showed that the blood flow in ischemic hindlimbs was significantly increased in the AGGF1 group compared to control mice at time points of 7, 14, and 28 days after DNA administration (n = 9/group, P = 0.049, 0.001, and 0.001, respectively). Increased blood flow in the AGGF1 group was correlated to increased density of CD31-positive vessels and decreased necrosis in muscle tissues injected with AGGF1 DNA compared with the control tissue injected with the empty vector. Ambulatory impairment was significantly reduced in the AGGF1 group compared to the control group (P = 0.004). The effect of AGGF1 was dose-dependent. At day 28 after gene transfer, AGGF1 was significantly better in increasing blood flow than FGF-2 (P = 0.034), although no difference was found for tissue necrosis and ambulatory impairment. CONCLUSIONS These data establish AGGF1 as a candidate therapeutic agent for therapeutic angiogenesis to treat PAD.
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Affiliation(s)
- Qiulun Lu
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, People’s Republic of China
| | - Yihong Yao
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, People’s Republic of China
| | - Yufeng Yao
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, People’s Republic of China
| | - Shizhi Liu
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, People’s Republic of China
| | - Yuan Huang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, People’s Republic of China
| | - Shan Lu
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, People’s Republic of China
| | - Ying Bai
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, People’s Republic of China
| | - Bisheng Zhou
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, People’s Republic of China
| | - Yan Xu
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, People’s Republic of China
| | - Lei Li
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, People’s Republic of China
| | - Nan Wang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, People’s Republic of China
| | - Li Wang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, People’s Republic of China
| | - Jie Zhang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, People’s Republic of China
| | - Xiang Cheng
- Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People’s Republic of China
| | - Gangjian Qin
- Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Wei Ma
- The First Hospital of Wuhan City, Wuhan, People’s Republic of China
| | - Chengqi Xu
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, People’s Republic of China
| | - Xin Tu
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, People’s Republic of China
| | - Qing Wang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, People’s Republic of China
- Center for Cardiovascular Genetics, Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
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Fujiwara H, Wake Y, Hashikawa-Hobara N, Makino K, Takatori S, Zamami Y, Kitamura Y, Kawasaki H. Endothelium-Derived Relaxing Factor–Mediated Vasodilation in Mouse Mesenteric Vascular Beds. J Pharmacol Sci 2012; 118:373-81. [DOI: 10.1254/jphs.11197fp] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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Cardinal TR, Struthers KR, Kesler TJ, Yocum MD, Kurjiaka DT, Hoying JB. Chronic hindlimb ischemia impairs functional vasodilation and vascular reactivity in mouse feed arteries. Front Physiol 2011; 2:91. [PMID: 22164145 PMCID: PMC3230861 DOI: 10.3389/fphys.2011.00091] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2011] [Accepted: 11/14/2011] [Indexed: 11/13/2022] Open
Abstract
Vasodilation of lower leg arterioles is impaired in animal models of chronic peripheral ischemia. In addition to arterioles, feed arteries are a critical component of the vascular resistance network, accounting for as much as 50% of the pressure drop across the arterial circulation. Despite the critical importance of feed arteries in blood flow control, the impact of ischemia on feed artery vascular reactivity is unknown. At 14 days following unilateral resection of the femoral–saphenous artery–vein pair, functional vasodilation of the profunda femoris artery was severely impaired, 11 ± 9 versus 152 ± 22%. Although endothelial and smooth muscle-dependent vasodilation were both impaired in ischemic arteries compared to control arteries (Ach: 40 ± 14 versus 81 ± 11%, SNP: 43 ± 12 versus and 85 ± 11%), the responses to acetylcholine and sodium nitroprusside were similar, implicating impaired smooth muscle-dependent vasodilation. Conversely, vasoconstriction responses to norepinephrine were not different between ischemic and control arteries, −68 ± 3 versus −66 ± 3%, indicating that smooth muscle cells were functional following the ischemic insult. Finally, maximal dilation responses to acetylcholine, ex vivo, were significantly impaired in the ischemic artery compared to control, 71 ± 9 versus 97 ± 2%, despite a similar generation of myogenic tone to the same intravascular pressure (80 mmHg). These data indicate that ischemia impairs feed artery vasodilation by impairing the responsiveness of the vascular wall to vasodilating stimuli. Future studies to examine the mechanistic basis for the impact of ischemia on vascular reactivity or treatment strategies to improve vascular reactivity following ischemia could provide the foundation for an alternative therapeutic paradigm for peripheral arterial occlusive disease.
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Affiliation(s)
- Trevor R Cardinal
- Biomedical Engineering, California Polytechnic State University San Luis Obispo, CA, USA
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Dillon EL, Casperson SL, Durham WJ, Randolph KM, Urban RJ, Volpi E, Ahmad M, Kinsky MP, Sheffield-Moore M. Muscle protein metabolism responds similarly to exogenous amino acids in healthy younger and older adults during NO-induced hyperemia. Am J Physiol Regul Integr Comp Physiol 2011; 301:R1408-17. [PMID: 21880862 DOI: 10.1152/ajpregu.00211.2011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The combination of increasing blood flow and amino acid (AA) availability provides an anabolic stimulus to the skeletal muscle of healthy young adults by optimizing both AA delivery and utilization. However, aging is associated with a blunted response to anabolic stimuli and may involve impairments in endothelial function. We investigated whether age-related differences exist in the muscle protein anabolic response to AAs between younger (30 ± 2 yr) and older (67 ± 2 yr) adults when macrovascular and microvascular leg blood flow were similarly increased with the nitric oxide (NO) donor, sodium nitroprusside (SNP). Regardless of age, SNP+AA induced similar increases above baseline (P ≤ 0.05) in macrovascular flow (4.3 vs. 4.4 ml·min(-1)·100 ml leg(-1) measured using indocyanine green dye dilution), microvascular flow (1.4 vs. 0.8 video intensity/s measured using contrast-enhanced ultrasound), phenylalanine net balance (59 vs. 68 nmol·min(-1)·100 ml·leg(-1)), fractional synthetic rate (0.02 vs. 0.02%/h), and model-derived muscle protein synthesis (62 vs. 49 nmol·min(-1)·100 ml·leg(-1)) in both younger vs. older individuals, respectively. Provision of AAs during NO-induced local skeletal muscle hyperemia stimulates skeletal muscle protein metabolism in older adults to a similar extent as in younger adults. Our results suggest that the aging vasculature is responsive to exogenous NO and that there is no age-related difference per se in AA-induced anabolism under such hyperemic conditions.
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Affiliation(s)
- E Lichar Dillon
- Divisions of Endocrinology and Metabolism, Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas 77555, USA
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Wang CH, Chen KT, Mei HF, Lee JF, Cherng WJ, Lin SJ. Assessment of mouse hind limb endothelial function by measuring femoral artery blood flow responses. J Vasc Surg 2011; 53:1350-8. [PMID: 21276693 DOI: 10.1016/j.jvs.2010.10.128] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Revised: 10/26/2010] [Accepted: 10/30/2010] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Substantial progress has been made in cell therapy strategies and in gene- and cytokine-introduced angiogenesis using a variety of mouse models, such as hind limb ischemia models. Endothelial function is an important target in evaluating the effects and outcomes of these potential therapies. Although animal models have been established for estimating endothelium-dependent function by measuring the blood flow responses in carotid and renal arteries and the abdominal aorta, a model specific for an indicated hind limb by measuring femoral artery blood flow (FABF) has not yet been established. METHODS A 2-day protocol was designed, including exploration of the segmental femoral artery on the first day, and evaluation of endothelium-dependent vasodilatation function the next day. By placing a transonic flow probe around the left femoral artery, the FABF in response to endothelium-dependent and endothelium-independent vasodilatory stimulations was reproducibly measured. Hemodynamic measurements, including the left FABF and mean arterial pressure, were recorded. RESULTS In normal controls, the baseline left FABF averaged 0.12 ± 0.01 mL/min. Acetylcholine increased the FABF up to 0.41 ± 0.02 mL/min. Rose bengal-associated photochemical injury was titrated to cause endothelial dysfunction but without disturbing the integrity of the endothelial layer. The response to acetylcholine significantly decreased 10 minutes after photochemical injury and was further impaired after 1 and 24 hours. However, the response to nitroprusside was preserved. A femoral and iliac artery wire-injury model was also introduced to cause endothelial and smooth muscle cell injury. One day after the wire injury, the responses to acetylcholine and nitroprusside injections were both remarkably attenuated. CONCLUSIONS This model can be widely used to analyze the in vivo endothelium-dependent vasodilatation function before and after a variety of therapeutic interventions on a mouse hind limb.
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Affiliation(s)
- Chao-Hung Wang
- Division of Cardiology, Department of Internal Medicine, Chang Gung Memorial Hospital at Keelung, Keelung, Taiwan.
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Reboul C, Gibault A, Tanguy S, Dauzat M, Obert P. Alteration of endothelium-mediated vasodilator response in the rat hindlimb vasculature consecutive to chronic hypoxic stress: NO and EDHF involvement. Vascul Pharmacol 2009; 51:154-61. [PMID: 19520187 DOI: 10.1016/j.vph.2009.05.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Revised: 04/23/2009] [Accepted: 05/28/2009] [Indexed: 11/30/2022]
Abstract
The previously documented impairment of hindlimb blood flow consecutive to chronic hypoxia might be related to endothelial vasomotor dysfunction. The aim of this study was to assess in-vivo the effect of chronic hypoxic stress on endothelium-mediated vasodilator response of hindlimb vascular bed, especially as regards to endothelium-derived hyperpolarizing factor (EDHF) and nitric oxide (NO) pathway contribution. Dark Agouti rats were randomly assigned to live at barometric pressure approximately 760 mmHg (N rats) or approximately 550 mmHg (CH rats). Under anesthesia, catheters were placed in the carotid artery for arterial pressure measurement, and in the saphenous vein and iliac artery for drug delivery. Hindlimb blood flow (HBF) was measured by transit-time ultrasound flowmetry, at baseline and during endothelium-dependent vasodilator response induced by intra-arterial injection of acetylcholine (0.75 ng and 7.5 ng) with and without specific blockers of NOS (L-NAME) and EDHF (Charybdotoxin+Apamin). HBF and hindlimb vascular conductance changes in response to ACh infusion were significantly lower in CH than in N rats. The mechanisms responsible for this blunted response involved impairment in both NO pathway and EDHF. The chronic hypoxia-induced alteration of NO pathway was mainly related to the bioavailability of its substrate l-Arginine, since the infusion of l-Arginine restored the endothelial response to ACh in CH rats to the level of N rats. These results demonstrate that the impairment in endothelium-mediated vasodilator response of the hindlimb vascular tree induced by chronic hypoxic stress involves both NO and EDHF.
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Affiliation(s)
- C Reboul
- EA4278, Research Laboratory: 'Physiology and physiopathology of Cardiovascular Adaptations to Exercise', Faculty of Sciences, Avignon University, Avignon, France.
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Edgley AJ, Tare M, Evans RG, Skordilis C, Parkington HC. In vivo regulation of endothelium-dependent vasodilation in the rat renal circulation and the effect of streptozotocin-induced diabetes. Am J Physiol Regul Integr Comp Physiol 2008; 295:R829-39. [DOI: 10.1152/ajpregu.00861.2007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We assessed the relative contributions of endothelium-derived relaxing factors to renal vasodilation in vivo and determined whether these are altered in established streptozotocin-induced diabetes. In nondiabetic rats, stimulation of the endothelium by locally administered ACh or bradykinin-induced transient renal hyperemia. Neither basal renal blood flow (RBF) nor renal hyperemic responses to ACh or bradykinin were altered by blockade of prostanoid production (indomethacin) or by administration of charybdotoxin (ChTx) plus apamin to block endothelium-derived hyperpolarizing factor (EDHF). In contrast, combined blockade of nitric oxide (NO) synthase, Nω-nitro-l-arginine methyl ester (l-NAME), and prostanoid production reduced basal RBF and the duration of the hyperemic responses to ACh and bradykinin and revealed a delayed ischemic response to ACh. Accordingly, l-NAME and indomethacin markedly reduced integrated (area under the curve) hyperemic responses to ACh and bradykinin. Peak increases in RBF in response to ACh and bradykinin were not reduced by l-NAME and indomethacin but were reduced by subsequent blockade of EDHF. l-NAME plus indomethacin and ChTx plus apamin altered RBF responses to endothelium stimulation in a qualitatively similar fashion in diabetic and nondiabetic rats. The integrated renal hyperemic responses to ACh and bradykinin were blunted in diabetes, due to a diminished contribution of the component abolished by l-NAME plus indomethacin. We conclude that NO dominates integrated hyperemic responses to ACh and bradykinin in the rat kidney in vivo. After prior inhibition of NO synthase, EDHF mediates transient renal vasodilation in vivo. Renal endothelium-dependent vasodilation is diminished in diabetes due to impaired NO function.
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Berhane Y, Bailey SR, Putignano C, Elliott J. Characterization of agonist-induced endothelium-dependent vasodilatory responses in the vascular bed of the equine digit. J Vet Pharmacol Ther 2008; 31:1-8. [PMID: 18177312 DOI: 10.1111/j.1365-2885.2007.00912.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The role of endothelium-derived relaxing factors was studied in the regulation of vascular responses in the Krebs perfused equine isolated digit. Perfusion pressure was recorded in response to bolus doses of 5-hydroxytryptamine (6 nmol) alone or co-administered with carbachol (CCh; 0.2 micromol), bradykinin (BK; 0.2 nmol), substance P (SP; 0.2 nmol) or sodium nitroprusside (SNP; 0.2 micromol). N(omega)-Nitro-L-Arginine methyl ester hydrochloride (L-NAME; 300 microm) caused partial but significant inhibition of CCh-induced vasodilatory response, whereas BK and SP-induced responses were resistant to L-NAME. High potassium (K(+), 30 mm) and the cytochrome P-450 (CYP) epoxygenase inhibitor, clotrimazole (10 microm) plus L-NAME (100 microm), completely abolished the CCh, BK and SP-induced vasodilatory responses, whereas the response to SNP was unaffected. In contrast, the L-NAME-resistant proportion of CCh, BK and SP-induced vasodilatory response was not inhibited by the highly selective CYP2C9 inhibitor, sulphaphenazole (10 microm). The cyclo-oxygenase inhibitor, ibuprofen (10 microm) did not affect the CCh, BK and SP-induced responses. These data demonstrate that CCh, BK and SP-induced relaxation in the equine digit involve a combination of the NO and endothelium-derived hyperpolarizing factor (EDHF) pathways. These results do not support the evidence for the involvement of CYP-derived epoxyeicosatrienoic acids and the exact nature of EDHF in the equine digit remains to be established.
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Affiliation(s)
- Y Berhane
- Department of Veterinary Basic Sciences, Royal Veterinary College, London, UK.
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Gaubert ML, Sigaudo-Roussel D, Tartas M, Berrut G, Saumet JL, Fromy B. Endothelium-derived hyperpolarizing factor as an in vivo back-up mechanism in the cutaneous microcirculation in old mice. J Physiol 2007; 585:617-26. [PMID: 17932144 DOI: 10.1113/jphysiol.2007.143750] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
There is now strong evidence that an endothelium-derived hyperpolarizing factor (EDHF), other than nitric oxide (NO) or prostaglandin (PG), exists for dilating arteries and arterioles. In vitro studies on isolated vessels pointed out a role for EDHF as a back-up mechanism when the NO pathway is impaired, but there was a lack of in vivo studies showing a functional role for EDHF. Ageing has pronounced effects on vascular function and particularly on endothelium-dependent relaxation, providing a novel situation in which to assess the contributions of EDHF. The purpose of the present study was thus to determine if, in vivo, there was a functional role for EDHF as a back-up mechanism in the cutaneous microcirculation in the ageing process. We investigated in vivo the contribution of each endothelial factor (NO, PG and EDHF) in the cutaneous vasodilatation induced by iontophoretic delivery of acetylcholine and local pressure application in young adult (6-7 months) and old (22-25 months) mice, using pharmacological inhibitors. The cutaneous vasodilator responses induced by acetylcholine and local pressure application were dependent upon NO and PG pathways in young adult mice, whereas they were EDHF-dependent in old mice. EDHF appears to serve as a back-up mechanism when ageing reaches pathological states in terms of the ability for NO and PG to relax cutaneous microvessels, allowing for persistent cutaneous vasodilatator responses in old mice. However, as a back-up mechanism, EDHF did not completely restore cutaneous vasodilatation, since endothelial responses were reduced in old mice compared to young adult mice.
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Affiliation(s)
- Marie Line Gaubert
- Integrative neuro-vascular biology, UMR CNRS 6214-INSERM 771, Medical School, University of Angers, France
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