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Akiyama T, Hirata T, Fujimoto T, Hatakeyama S, Yamazaki R, Nomura T. The Natural-Mineral-Based Novel Nanomaterial IFMC Increases Intravascular Nitric Oxide without Its Intake: Implications for COVID-19 and beyond. NANOMATERIALS 2020; 10:nano10091699. [PMID: 32872395 PMCID: PMC7559745 DOI: 10.3390/nano10091699] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 08/16/2020] [Accepted: 08/27/2020] [Indexed: 01/22/2023]
Abstract
There are currently no promising therapy strategies for either the treatment or prevention of novel coronavirus disease 2019 (COVID-19), despite the urgent need. In addition to respiratory diseases, vascular complications are rapidly emerging as a key threat of COVID-19. Existing nitric oxide (NO) therapies have been shown to improve the vascular system; however, they have different limitations in terms of safety, usability and availability. In light of this, we hypothesise that a natural-mineral-based novel nanomaterial, which was developed based on NO therapy, might be a viable strategy for the treatment and prevention of COVID-19. The present study examined if it could induce an increase of intravascular NO, vasodilation and the consequent increase of blood flow rate and temperature in a living body. The intravascular NO concentration in the hepatic portal of rats was increased by 0.17 nM over 35.2 s on average after its application. An ultrasonic Doppler flow meter showed significant increases in the blood flow rate and vessel diameter, but no difference in the blood flow velocity. These were corroborated by measurements of human hand surface temperature. To our knowledge, this result is the first evidence where an increase of intravascular NO and vasodilation were induced by bringing a natural-mineral-based nanomaterial into contact with or close to a living body. The precise mechanisms remain a matter for further investigation; however, we may assume that endothelial NO synthase, haemoglobin and endothelium-derived hyperpolarising factor are deeply involved in the increase of intravascular NO.
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Affiliation(s)
- Tomohiro Akiyama
- Advanced Research Laboratories, Tokyo City University, Tokyo 158-8557, Japan;
- Graduate School of Information Technology, Kobe Institute of Computing, Kobe 650-0001, Japan
- Graduate School of Education, Kyoto University, Kyoto 606-8501, Japan
- Graduate School of Global Environmental Studies, Sophia University, Tokyo 102-8554, Japan
- Correspondence: (T.A.); (T.H.)
| | - Takamichi Hirata
- Advanced Research Laboratories, Tokyo City University, Tokyo 158-8557, Japan;
- Graduate School of Integrative Science and Engineering, Electrical Engineering and Chemistry, Tokyo City University, Tokyo 158-8557, Japan; (S.H.); (R.Y.)
- Correspondence: (T.A.); (T.H.)
| | - Takahiro Fujimoto
- Advanced Research Laboratories, Tokyo City University, Tokyo 158-8557, Japan;
- Clinic F Laser Medicine & Surgery, Tokyo 102-0083, Japan
| | - Shinnosuke Hatakeyama
- Graduate School of Integrative Science and Engineering, Electrical Engineering and Chemistry, Tokyo City University, Tokyo 158-8557, Japan; (S.H.); (R.Y.)
| | - Ryuhei Yamazaki
- Graduate School of Integrative Science and Engineering, Electrical Engineering and Chemistry, Tokyo City University, Tokyo 158-8557, Japan; (S.H.); (R.Y.)
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Umbrello M, Dyson A, Pinto BB, Fernandez BO, Simon V, Feelisch M, Singer M. Short-term hypoxic vasodilation in vivo is mediated by bioactive nitric oxide metabolites, rather than free nitric oxide derived from haemoglobin-mediated nitrite reduction. J Physiol 2014; 592:1061-75. [PMID: 24396056 DOI: 10.1113/jphysiol.2013.255687] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Local increases in blood flow--'hypoxic vasodilation'--confer cellular protection in the face of reduced oxygen delivery. The physiological relevance of this response is well established, yet ongoing controversy surrounds its underlying mechanisms. We sought to confirm that early hypoxic vasodilation is a nitric oxide (NO)-mediated phenomenon and to study putative pathways for increased levels of NO, namely production from NO synthases, intravascular nitrite reduction, release from preformed stores and reduced deactivation by cytochrome c oxidase. Experiments were performed on spontaneously breathing, anaesthetized, male Wistar rats undergoing short-term systemic hypoxaemia, who received pharmacological inhibitors and activators of the various NO pathways. Arterial blood pressure, cardiac output, tissue oxygen tension and the circulating pool of NO metabolites (oxidation, nitrosation and nitrosylation products) were measured in plasma and erythrocytes. Hypoxaemia caused a rapid and sustained vasodilation, which was only partially reversed by non-selective NO synthase inhibition. This was associated with significantly lower plasma nitrite, and marginally elevated nitrate levels, suggestive of nitrite bioinactivation. Administration of sodium nitrite had little effect in normoxia, but produced significant vasodilation and increased nitrosylation during hypoxaemia that could not be reversed by NO scavenging. Methodological issues prevented assessment of the contribution, if any, of reduced deactivation of NO by cytochrome c oxidase. In conclusion, acute hypoxic vasodilation is an adaptive NO-mediated response conferred through bioactive metabolites rather than free NO from haemoglobin-mediated reduction of nitrite.
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Affiliation(s)
- Michele Umbrello
- Bloomsbury Institute of Intensive Care Medicine, University College London, Cruciform Building, Gower Street, London WC1E 6BT, UK.
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Creteur J, Neves AP, Vincent JL. Near-infrared spectroscopy technique to evaluate the effects of red blood cell transfusion on tissue oxygenation. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2009; 13 Suppl 5:S11. [PMID: 19951383 PMCID: PMC2786113 DOI: 10.1186/cc8009] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Introduction The aim of this study was to evaluate the effects of red blood cell (RBC) transfusions on muscle tissue oxygenation, oxygen metabolism and microvascular reactivity in critically ill patients using near-infrared spectroscopy (NIRS) technology. Methods This prospective, observational study included 44 consecutive patients hospitalized in the 31-bed, medical-surgical intensive care unit of a university hospital with anemia requiring red blood cell transfusion. Thenar tissue oxygen saturation (StO2) and muscle tissue hemoglobin index (THI) were measured using a tissue spectrometer (InSpectra™ Model 325; Hutchinson Technology Inc., Hutchinson, MN, USA). A vaso-occlusive test was performed before and 1 hour after RBC transfusion by rapid inflation of a pneumatic cuff around the upper arm. The following variables were recorded: THI, the StO2 desaturation slope during the occlusion (%/minute) and the StO2 upslope of the reperfusion phase following the ischemic period (%/second). Muscle oxygen consumption (NIR VO2; arbitrary units) was calculated as the product of the inverse StO2 desaturation slope and the mean THI over the first minute of arterial occlusion. Results Blood transfusion resulted in increases in hemoglobin (from 7.1 (6.7 to 7.7) to 8.4 (7.1 to 9) g/dl; P < 0.01) and in oxygen delivery (from 306 (259 to 337) to 356 (332 to 422) ml/minute/m2; P < 0.001). However, systemic VO2 was unchanged. RBC transfusion did not globally affect NIRS-derived variables, but there was considerable interindividual variation. Changes in the StO2 upslope of the reperfusion phase after transfusion were negatively correlated with baseline StO2 upslope of the reperfusion phase (r2 = 0.42; P < 0.0001). Changes in NIR VO2 after transfusion were also negatively correlated with baseline NIR VO2 (r2 = 0.48; P = 0.0015). There were no correlations between RBC storage time and changes in StO2 slope or NIR VO2. Conclusions Muscle tissue oxygenation, oxygen consumption and microvascular reactivity are globally unaltered by RBC transfusion in critically ill patients. However, muscle oxygen consumption and microvascular reactivity can improve following transfusion in patients with alterations of these variables at baseline.
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Affiliation(s)
- Jacques Creteur
- Department of Intensive Care, Erasme University Hospital, Université Libre de Bruxelles, Route de Lennik 808, 1070 Brussels, Belgium
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Creteur J, Carollo T, Soldati G, Buchele G, De Backer D, Vincent JL. The prognostic value of muscle StO2 in septic patients. Intensive Care Med 2007; 33:1549-56. [PMID: 17572876 DOI: 10.1007/s00134-007-0739-3] [Citation(s) in RCA: 255] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2006] [Accepted: 05/11/2007] [Indexed: 12/25/2022]
Abstract
OBJECTIVE To quantify sepsis-induced alterations in changes in muscle tissue oxygenation (StO(2)) after an ischemic challenge using near-infrared spectroscopy (NIRS), and to test the hypothesis that these alterations are related to outcome. DESIGN Prospective study. SETTING Thirty-one-bed, university hospital Department of Intensive Care. PATIENTS Seventy-two patients with severe sepsis or septic shock, 18 hemodynamically stable, acutely ill patients without infection, and 18 healthy volunteers. INTERVENTIONS Three-minute occlusion of the brachial artery using a cuff inflated 50[Symbol: see text]mmHg above systolic arterial pressure. MEASUREMENTS AND MAIN RESULTS Thenar eminence StO(2) was measured continuously by NIRS before (StO(2)baseline), during, and after the 3-min occlusion. Changes in StO(2) were assessed by the slope of increase in StO(2) during the first 14 s following the ischemic period and by the difference between the maximum StO(2) and StO(2)baseline (Delta). The slope was lower in septic patients than in controls and volunteers [2.3 (1.3-3.6), 4.8 (3.5-6.0), and 4.7 (3.2-6.3) %/s, p < 0.001]. Delta was also significantly lower in septic patients than in the other groups. Slopes were lower in septic patients with than without shock [2.0 (1.2-2.9) vs 3.2 (1.8-4.5) %/s, p < 0.05]. In 52 septic patients, in whom the slope was obtained every 24 h for 48 h, slopes were higher in survivors than in non-survivors and tended to increase in survivors but not in non-survivors. CONCLUSIONS Altered recovery in StO(2) after an ischemic challenge is frequent in septic patients and more pronounced in the presence of shock. The presence and persistence of these alterations in the first 24[Symbol: see text]h of sepsis are associated with worse outcome.
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Affiliation(s)
- Jacques Creteur
- Erasme University Hospital, Free University of Brussels, Department of Intensive Care, Route de Lennik 808, 1070 Brussels, Belgium
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Edmunds NJ, Marshall JM. Vasodilatation, oxygen delivery and oxygen consumption in rat hindlimb during systemic hypoxia: roles of nitric oxide. J Physiol 2001; 532:251-9. [PMID: 11283239 PMCID: PMC2278515 DOI: 10.1111/j.1469-7793.2001.0251g.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
We have investigated the relationship between O2 delivery (DO2) and O2 consumption (VO2) in hindlimb muscle of anaesthetised rats during progressive systemic hypoxia. Since muscle vasodilatation that occurs during hypoxia is nitric oxide (NO) dependent, we examined the effects of the NO synthase (NOS) inhibitor nitro-L-arginine methyl ester (L-NAME). In control rats (n = 8), femoral vascular conductance (FVC) increased at each level of hypoxia. Hindlimb DO2 decreased with the severity of hypoxia, but muscle VO2 was maintained until the critical DO2 value (DO2,crit) was reached at 0.64 +/- 0.06 ml O2 min-1 kg-1; below this VO2 declined linearly with DO2. This is a novel finding for the rat but is comparable to the biphasic relationship seen in the dog. In another group of rats (n = 6), L-NAME caused hindlimb vasoconstriction and attenuated the hypoxia-evoked increases in FVC DO2 was so low after L-NAME administration that VO2 was dependent on DO2 at all levels of hypoxia. In a further group (n = 8), femoral blood flow and DO2 were restored after L-NAME by infusion of the NO donor sodium nitroprusside (20 g x kg(-1) x min(-1). Thereafter, hypoxia-evoked increases in FVC were fully restored. Nevertheless, DO2,crit was increased relative to control (0.96 +/- 0.07 ml O2 min(-1) x kg(-1), P < 0.01). As NOS inhibition limited the ability of muscle to maintain VO2 during hypoxia, we propose that hypoxia-induced dilatation of terminal arterioles, which improves tissue O2 distribution, is mediated by NO. However, since the hypoxia-evoked increase in FVC was blocked by L-NAME but restored by the NO donor, we propose that the dilatation of proximal arterioles is dependent on tonic levels of NO, rather than mediated by NO.
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Affiliation(s)
- N J Edmunds
- Department of Physiology, The Medical School, University of Birmingham, Vincent Drive, Birmingham B15 2TT, UK.
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Eichelbrönner O, Sielenkämper A, D'Almeida M, Ellis CG, Sibbald WJ, Chin-Yee IH. Effects of FI(O(2)) on hemodynamic responses and O(2) transport during RSR13-induced reduction in P(50). THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:H290-8. [PMID: 10409208 DOI: 10.1152/ajpheart.1999.277.1.h290] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Reduced Hb-O(2) affinity facilitates O(2) release to tissue but may impair pulmonary O(2) uptake, affecting cardiac output and systemic vascular resistance (SVR). We studied the effects of shifting the O(2)-dissociation curve (ODC) to the right with a continuous infusion of RSR13, an allosteric modifier of Hb, and of different inspired O(2) fractions (FI(O(2))) on arterial O(2) saturations (Sa(O(2))) in Hb and on hemodynamics in nonanesthetized rats. At an FI(O(2)) of 0.21, Sa(O(2)) fell during RSR13 from 95 to 81%. Elevation of FI(O(2)) to 0.30 returned Sa(O(2)) to baseline in the RSR13 group. The decrease in mean arterial pressure (MAP) was significantly greater in the control than in the RSR13 group at 30% O(2). Cardiac index (CI) increased only during RSR13 at 21% O(2) and returned to baseline at 30% O(2). In contrast, SVR decreased after RSR13 was infused at 21% O(2) but returned to baseline at 30%O(2), whereas controls showed the opposite, a sustained SVR. In the follow-up period, when 21 O(2)% was reestablished and mild anemia was present, MAP and SVR fell significantly more in controls, whereas CI only increased in controls. Lactate was significantly lower in the RSR13 than in the control group during RSR13 and the follow-up period. These results demonstrate that 1) continuous infusion of RSR13 produces a constant shift in the O(2) tension at which Hb is 50% saturated (P(50)), 2) FI(O(2)) of 0.30 compensates for the effects of increased P(50) on pulmonary O(2) loading, and 3) right-shifted ODC combined with supplemental O(2) may improve tissue O(2) availability.
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Affiliation(s)
- O Eichelbrönner
- A. C. Burton Vascular Biology Laboratory, University of Western Ontario, London, Ontario, Canada N6A 4G5
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Ward ME. Dilation of rat diaphragmatic arterioles by flow and hypoxia: roles of nitric oxide and prostaglandins. J Appl Physiol (1985) 1999; 86:1644-50. [PMID: 10233130 DOI: 10.1152/jappl.1999.86.5.1644] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The in vitro responses to ACh, flow, and hypoxia were studied in arterioles isolated from the diaphragms of rats. The endothelium was removed in some vessels by low-pressure air perfusion. In endothelium-intact arterioles, pressurized to 70 mmHg in the absence of luminal flow, ACh (10(-5) M) elicited dilation (from 103 +/- 10 to 156 +/- 13 microm). The response to ACh was eliminated by endothelial ablation and by the nitric oxide synthase antagonists NG-nitro-L-arginine (L-NNA; 10(-5) M) and NG-nitro-L-arginine methyl ester (L-NAME, 10(-5) M) but not by indomethacin (10(-5) M). Increases in luminal flow (5-35 microl/min in 5 microl/min steps) at constant distending pressure (70 mmHg) elicited dilation (from 98 +/- 8 to 159 +/- 12 microm) in endothelium-intact arterioles. The response to flow was partially inhibited by L-NNA, L-NAME, and indomethacin and eliminated by endothelial ablation and by concurrent treatment with L-NAME and indomethacin. The response to hypoxia was determined by reducing the periarteriolar PO2 from 100 to 25-30 Torr by changing the composition of the gas used to bubble the superfusing solution. Hypoxia elicited dilation (from 110 +/- 9 to 165 +/- 12 microm) in endothelium-intact arterioles but not in arterioles from which the endothelium had been removed. Hypoxic vasodilation was eliminated by treatment with indomethacin and was not affected by L-NAME or L-NNA. In rat diaphragmatic arterioles, the response to ACh is dependent on endothelial nitric oxide release, whereas the response to hypoxia is mediated by endothelium-derived prostaglandins. Flow-dilation requires that both nitric oxide and cyclooxygenase pathways be intact.
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Affiliation(s)
- M E Ward
- Divisions of Pulmonary and Critical Care Medicine, Royal Victoria Hospital and Meakins-Christie Laboratories, McGill University, Montreal, Quebec, Canada H2X 2P2.
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Saetre T, Gundersen Y, Smiseth OA, Scholz T, Carlsen H, Nordsletten L, Lilleaasen P, Sautner T, Függer R, Aasen AO. Hepatic oxygen metabolism in porcine endotoxemia: the effect of nitric oxide synthase inhibition. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 275:G1377-85. [PMID: 9843775 DOI: 10.1152/ajpgi.1998.275.6.g1377] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The role of endotoxin (lipopolysaccharide, LPS) and nitric oxide in hepatic oxygen metabolism was investigated in 36 pigs receiving 1) LPS (1.7 microgram. kg-1. h-1) for 7 h and NG-nitro-L-arginine methyl ester (L-NAME; 25 mg/kg) after 3 h, 2) LPS, 3) NaCl and L-NAME, and 4) NaCl. Infusion of LPS reduced hepatic oxygen delivery (DO2H) from 60 +/- 4 to 30 +/- 5 ml/min (P < 0.05) and increased the oxygen extraction ratio from 0.29 +/- 0.07 to 0.68 +/- 0.04 after 3 h (P < 0.05). Hepatic oxygen consumption (VO2H) was maintained (18 +/- 4 and 21 +/- 4 ml/min, change not significant), but acidosis developed. Administration of L-NAME during endotoxemia caused further reduction of DO2H from 30 +/- 3 to 13 +/- 2 ml/min (P < 0.05) and increased hepatic oxygen extraction ratio from 0.46 +/- 0.04 to 0.80 +/- 0.03 (P < 0.05). There was a decrease in VO2H from 13 +/- 2 to 9 +/- 2 ml/min that did not reach statistical significance, probably representing a type II error. Acidosis was aggravated. Administration of L-NAME in the absence of endotoxin also increased the hepatic oxygen extraction ratio, but no acidosis developed. In a different experiment, liver blood flow was mechanically reduced in the presence and absence of endotoxin, comparable to the flow reductions caused by L-NAME. The increase in hepatic oxygen extraction ratio (0.34) and maximum hepatic oxygen extraction ratio (approximately 0.90) was similar whether DO2H was reduced by occlusion or by L-NAME. We concluded that L-NAME has detrimental circulatory effects in this model. However, neither endotoxin nor L-NAME seemed to prevent the ability of the still circulated parts of the liver to increase hepatic oxygen extraction ratio to almost maximum when oxygen delivery was reduced. The effect of L-NAME on oxygen transport thus seems to be caused by a reduction in DO2H rather than by alterations in oxygen extraction capabilities.
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Affiliation(s)
- T Saetre
- Institute for Surgical Research, The National Hospital, 0407 Oslo, Norway
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King-VanVlack CE, Curtis SE, Mewburn JD, Cain SM, Chapler CK. Endothelial modulation of neural sympathetic vascular tone in canine skeletal muscle. J Appl Physiol (1985) 1998; 85:1362-7. [PMID: 9760329 DOI: 10.1152/jappl.1998.85.4.1362] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The effect of nitric oxide synthase (NOS) inhibition and endothelin-A (ETA)-receptor blockade on neural sympathetic control of vascular tone in the gastrocnemius muscle was examined in anesthetized dogs under conditions of constant flow. Muscle perfusion pressure (MPP) was measured before and after NOS inhibition (Nomega-nitro-L-arginine methyl ester; L-NAME) and ETA-receptor blockade [cyclo-(D-Trp-d-Asp-Pro-D-Val-Leu); BQ-123]. Zero and maximum sympathetic nerve activities were achieved by sciatic nerve cold block and stimulation, respectively. In group 1 (n = 6), MPP was measured 1) before nerve cold block, 2) during nerve cold block, and 3) during nerve stimulation. Measurements under these conditions were repeated after L-NAME and then BQ-123. The same protocol was followed in group 2 (n = 6) except that the order of L-NAME and BQ-123 was reversed. MPP and muscle vascular resistance (MVR) increased after L-NAME and then decreased to control values after BQ-123. MVR decreased after BQ-123 alone and, with the addition of L-NAME, increased to a level not different from that observed during the control period. MVR fell during nerve cold block. This response was not affected by administration of L-NAME followed by BQ-123, but it was attenuated by administration of BQ-123 before L-NAME. The constrictor response during sympathetic nerve stimulation was enhanced by L-NAME; no further effect was observed with BQ-123, nor was the response affected when BQ-123 was given first. These findings indicate that endothelin contributes to 1) basal vascular tone in skeletal muscle and 2) the increase in skeletal muscle vascular resistance after NOS inhibition. Finally, nitric oxide "buffers" the degree of constriction in skeletal muscle vasculature during maximal sympathetic stimulation.
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Affiliation(s)
- C E King-VanVlack
- School of Rehabilitation Therapy, Queen's University, Kingston, Ontario, Canada K7L 3N6
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Curtis SE, Walker TA, Bradley WE, Cain SM. Raising P50 increases tissue PO2 in canine skeletal muscle but does not affect critical O2 extraction ratio. J Appl Physiol (1985) 1997; 83:1681-9. [PMID: 9375339 DOI: 10.1152/jappl.1997.83.5.1681] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Affinity of hemoglobin (Hb) for O2 determines in part the rate of O2 diffusion from capillaries to myocytes by altering capillary PO2. We hypothesized that a decrease in Hb O2 affinity (increased P50) would increase capillary and tissue PO2 (PtiO2) and improve O2 consumption during ischemia. To test this hypothesis, blood flow to the pump-perfused left hindlimb of 18 anesthetized and paralyzed dogs was progressively decreased over 90 min while hindlimb O2 consumption and O2 delivery (QO2) and PtiO2 were measured at the muscle surface. Arterial PO2 was maintained at 150 +/- 10 Torr in all dogs. We increased P50 by 12.3 +/- 0.9 (SE) Torr in nine dogs with RSR-13, an allosteric modifier of Hb. This decreased arterial O2 saturation to 90-92% but increased mean PtiO2 from 35.5 +/- 11.6 to 44.1 +/- 15.2 (SD) Torr (P < 0.05) with no change in controls (n = 9). O2 extraction ratio at critical QO2 was 74 +/- 2% in controls and 79 +/- 1% in RSR-13-treated dogs (P = not significant). PtiO2 was 30-40% higher in the RSR-13-treated group at any QO2 above critical but did not differ between groups below critical QO2. Perfusion heterogeneity and convergence of the dissociation curves near critical QO2 may have mitigated any effect of increased P50 on O2 diffusion. Still, increasing P50 by 12 Torr with RSR-13 significantly increased PtiO2 at QO2 values above critical.
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Affiliation(s)
- S E Curtis
- Department of Pediatrics, University of Alabama at Birmingham 35294, USA
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Zhang H, Rogiers P, Smail N, Cabral A, Preiser JC, Peny MO, Vincent JL. Effects of nitric oxide on blood flow distribution and O2 extraction capabilities during endotoxic shock. J Appl Physiol (1985) 1997; 83:1164-73. [PMID: 9338425 DOI: 10.1152/jappl.1997.83.4.1164] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The effects of the nitric oxide (NO) synthase inhibitor NG-monomethyl-L-arginine (L-NMMA) and the NO donor 3-morpholinosydnonimine (SIN-1) were tested in 18 endotoxic dogs. L-NMMA infusion (10 mg . kg-1 . h-1) increased arterial and pulmonary artery pressures and systemic and pulmonary vascular resistances but decreased cardiac index, left ventricular stroke work index, and blood flow to the hepatic, portal, mesenteric, and renal beds. SIN-1 infusion (2 microg . kg-1 . min-1) increased cardiac index; left ventricular stroke work index; and hepatic, portal, and mesenteric blood flow. It did not significantly influence arterial and pulmonary artery pressures but decreased renal blood flow. The critical O2 delivery was similar in the L-NMMA group and in the control group (13.3 +/- 1.6 vs. 12.8 +/- 3.3 ml . kg-1 . min-1) but lower in the SIN-1 group (9.1 +/- 1.8 ml . kg-1 . min-1, both P < 0.05). The critical O2 extraction ratio was also higher in the SIN-1 group than in the other groups (58.7 +/- 10.6 vs. 42.2 +/- 7.6% in controls, P < 0.05; 43.0 +/- 15.5% in L-NMMA group, P = not significant). We conclude that NO is not implicated in the alterations in O2 extraction capabilities observed early after endotoxin administration.
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Affiliation(s)
- H Zhang
- Department of Intensive Care, Erasme University Hospital, Free University of Brussels, B-1070 Brussels, Belgium
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Green LR, Bennet L, Hanson MA. The role of nitric oxide synthesis in cardiovascular responses to acute hypoxia in the late gestation sheep fetus. J Physiol 1996; 497 ( Pt 1):271-7. [PMID: 8951728 PMCID: PMC1160929 DOI: 10.1113/jphysiol.1996.sp021766] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
1. In fetal sheep (123-129 days gestation) we investigated the effect of acute isocapnic hypoxia (Pa,O2, 12 +/- 0.6 mmHg) on the fetal heart rate (FHR), mean systemic arterial blood pressure (MAP), carotid blood flow (CBF), femoral blood flow (FBF), carotid vascular resistance (CVR) and femoral vascular resistance (FVR) with the infusion of either the nitric oxide synthase (NOS) inhibitor NG-nitro-L-arginine methyl ester (L-NAME) or saline vehicle. 2. During normoxia, CBF was lower (P < 0.05) and MAP, FVR and CVR were higher with L-NAME than with vehicle infusion (P < 0.01, P < 0.05 and P < 0.01, respectively). FHR fell 15 min after the onset of L-NAME infusion (P < 0.05). During hypoxia in both groups, FHR showed an initial rapid fall (P < 0.05) and subsequent return to prehypoxic levels, and there was a fall in FBF (P < 0.01). MAP increased during hypoxia with vehicle (P < 0.05) but not L-NAME infusion: thus MAP was similar during hypoxia in the two groups. The rebound tachycardia seen during recovery in the vehicle group (P < 0.01) was not evident in the L-NAME group. The rise in CBF and fall in CVR during hypoxia with vehicle (P < 0.01 and P < 0.05, respectively) was absent with L-NAME infusion. FVR rose during hypoxia in both groups (P < 0.05). 3. Thus NOS inhibition alters basal systemic vascular tone in the late gestation fetus. The rise in CBF and fall in CVR during hypoxia is absent with NOS inhibition.
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Affiliation(s)
- L R Green
- Department of Obstetrics & Gynaecology, University College, London, UK
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Ward ME. Effect of inhibition of nitric oxide synthesis on the diaphragmatic microvascular response to hypoxia. J Appl Physiol (1985) 1996; 81:1633-41. [PMID: 8904580 DOI: 10.1152/jappl.1996.81.4.1633] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The purpose of this study was to determine the effect of inhibition of nitric oxide (NO) release on the diaphragmatic microvascular responses to hypoxia. In alpha-chloralose-anesthetized mongrel dogs, the microcirculation of the vascularly isolated ex vivo left hemidiaphragm was studied by intravital microscopy. The diaphragm was pump perfused with blood diverted from the femoral artery through a series of membrane oxygenators. The responses to supramaximal concentrations of sodium nitroprusside, moderate hypoxia (phrenic venous PO2 27 Torr), and severe hypoxia (phrenic venous PO2 15 Torr) were recorded before and after an infusion of NG-nitro-L-arginine (L-NNA; 6 x 10(-4) M) into the phrenic circulation for 20 min. Under control conditions, diaphragmatic blood flow was 12.4 +/- 1.1 ml.min-1.100g-1. Diaphragmatic blood flows recorded during moderate and severe hypoxia were 15.6 +/- 1.2 and 24.3 +/- 1.5 ml.min-1. 100 g-1, respectively (P < 0.05 for both compared with control values). Treatment with L-NNA reduced diaphragmatic blood flow to 9.6 +/- 0.8 ml.min-1.100 g-1 under control conditions (P < 0.05) and caused arteriolar vasoconstriction to a degree that was dependent on vessel size (i.e., larger vessels constricted more than smaller vessels). L-NNA eliminated the increase in blood flow during moderate hypoxia and inhibited arteriolar dilation by an amount that was related to vessel size (i.e., dilation of larger vessels was inhibited more than that of smaller vessels). Inhibition of NO synthesis had no effect on the increase in diaphragmatic blood flow (23.6 +/- 1.9 ml.min-1.100 g-1; P > 0.05 compared with that during severe hypoxia before treatment with L-NNA) or arteriolar diameters during severe hypoxia. NO release plays a role in the diaphragmatic vascular response to hypoxia, but this role is limited to dilation of larger arterioles during hypoxia of moderate severity.
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Affiliation(s)
- M E Ward
- Division of Critical Care, Royal Victoria Hospital, McGill University, Montreal, Quebec, Canada.
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Winn MJ, Vallet B, Curtis SE, Chapler CK, King CE, Cain SM. Critical oxygen extraction in dog hindlimb after inhibition of nitric oxide synthase and cyclooxygenase systems. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1994; 361:295-301. [PMID: 7541175 DOI: 10.1007/978-1-4615-1875-4_48] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- M J Winn
- Department of Pharmacology, University of Alabama at Birmingham 35294, USA
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