EDHF-mediated Endothelial Function Research Articles

Protection of coronary endothelial function during cardiac surgery: potential of targeting endothelial ion channels in cardioprotection.

Vascular endothelium plays a critical role in the control of blood flow by producing vasoactive factors to regulate vascular tone. Ion channels, in particular, K+ channels and Ca2+-permeable channels in endothelial cells, are essential to the production and function of endothelium-derived vasoactive factors. Impairment of coronary endothelial function occurs in open heart surgery that may result in reduction of coronary blood flow and thus in an inadequate myocardial perfusion. Hyperkalemic exposure and concurrent ischemia-reperfusion during cardioplegic intervention compromise NO and EDHF-mediated function and the impairment involves alterations of K+ channels, that is, KATP and KCa, and Ca2+-permeable TRP channels in endothelial cells. Pharmacological modulation of these channels during ischemia-reperfusion and hyperkalemic exposure show promising results on the preservation of NO and EDHF-mediated endothelial function, which suggests the potential of targeting endothelial K+ and TRP channels for myocardial protection during cardiac surgery.

Procaine in Cardioplegia: The Effect on EDHF-Mediated Function in Porcine Coronary Arteries

Hyperkalemia in cardioplegia impairs the endothelium-derived hyperpolarizing factor (EDHF)-mediated function. This study examined the effect of procaine in cardioplegia on the EDHF-mediated response in porcine coronary arteries. An isometric force study was performed in a myograph. Two rings taken from the same artery (diameter 200-450 microm) were incubated with Krebs solution (group I) or 20 mM K+ (group II) with/without procaine (1 mM) at 37 degrees C for 1 hour. The EDHF-mediated relaxation was induced by bradykinin (BK, -10 approximately -6.5 log M) after U46619 (-8 log M, in group I) or K+-precontraction (in group II) in the presence of indomethacin (7 microM), NG-nitro-L-arginine (300 microM), and hemoglobin (20 microM). The membrane potential of a single smooth muscle cell was measured by a microelectrode after superfusion with Krebs solution with/without procaine for 1 hour. The EDHF-mediated relaxation was increased by the treatment with procaine with the EC50 shifted leftward (97.3 +/- 0.6% vs. 83.0 +/- 5.1% at -7 log M and 99.4 +/- 0.6% vs. 96.7 +/- 1.6% at -6.5 log M, p < 0.05; EC50: -8.57 +/- 0.24 vs. -7.92 +/- 0.23 log M, p < 0.05). Procaine decreased the BK-induced hyperpolarization from -72.3 +/- 0.7 mV to -68.8 +/- 0.8 mV (-6.5 log M, p < 0.01). The EDHF-mediated relaxation in arteries exposed to 20 mM K+ was not altered by procaine (49.9 +/- 7.4% vs. 55.8 +/- 7.6%, p > 0.05). In the coronary arteries, procaine has a depolarizing effect but it enhances EDHF-mediated relaxation. Addition of procaine in cardioplegia did not change the EDHF-mediated endothelial function.

Role of NO and EDHF-mediated endothelial function in the porcine pulmonary circulation: Comparison between pulmonary artery and vein

Objective To compare electrophysiological measurement of nitric oxide (NO) release and endothelium-derived hyperpolarizing factor (EDHF)-mediated endothelial function in porcine pulmonary arteries and veins. Methods Isolated pulmonary interlobular arteries (PA) and veins (PV) were obtained from a local slaughterhouse. By using a NO-specific electrode and a conventional intracellular microelectrode, the amount of NO released from endothelial cells and hyperpolarization of smooth muscle cells were investigated. The bradykinin (BK)-induced relaxation in the precontraction by U 46619 was examined in the absence or presence of N G-nitro- l-arginine ( l-NNA), indomethacin (INDO) plus oxyhemoglobin (HbO). Results The basal release of NO was 7.0 ± 1.2 nmol/L in PA ( n = 8) and 5.5 ± 1.6 nmol/L in PV ( n = 8, p < 0.01). BK-induced release of NO was 160.4 ± 10.3 nmol/L in PA ( n = 8) and 103.0 ± 14.7 nmol/L in PV ( n = 8, p < 0.001) with longer releasing duration in PA than in PV (14.3 ± 1.3 vs. 12.1 ± 0.8 min, p < 0.01). BK evoked an endothelium-dependent hyperpolarization and relaxation that were reduced by l-NNA, INDO, and HbO (hyperpolarization: 12.8 ± 1.3 vs. 8.0 ± 1.4 mV in PA, n = 6, p < 0.001 and 8.3 ± 1.4 vs. 3.0 ± 0.8 mV in PV, n = 6, p < 0.001; relaxation: 92.8 ± 3.1% vs. 19.6 ± 11.1% in PA n = 8, p < 0.001 and 70.3 ± 7.9% vs. 6.0 ± 6.8% in PV, n = 8, p < 0.001). Both hyperpolarization (8.0 ± 1.4 vs. 3.0 ± 0.8 mV, p < 0.001) and relaxation (19.6 ± 11.1% vs. 6.0 ± 6.8%, p < 0.01) were greater in PA than in PV. Conclusions Both NO and EDHF play an important role in regulation of porcine pulmonary arterial and venous tones. The more significant role of NO and EDHF is revealed in pulmonary arteries than in veins.

Cellular Electrophysiological and Mechanical Effects of Celsior Solution on Endothelial Function in Resistance Coronary Arteries

We investigated a relatively new organ preservation (Celsior) solution regarding its effect on the endothelium-derived hyperpolarizing factor (EDHF)-mediated function with comparison to St. Thomas Hospital (ST) solution. The EDHF-mediated relaxation was induced by bradykinin (BK, -10 to -6.5 logM) in the presence of inhibitors of nitric oxide and prostacyclin in porcine small resistance coronary arteries, before and after incubation in ST (Group Ia, n=11), Celsior (Group Ib, n=13), or Krebs (Group Ic, control, n=12) at 4 degrees C for 4 hr. The EDHF-mediated hyperpolarization of the membrane potential of smooth muscle cells was measured by microelectrode with simultaneous relaxation after cold storage in ST (IIa, n=7), Celsior (IIb, n=6), or Krebs (IIc, control, n=6), or followed by washout with Krebs (ST: IIIa, n=6, Celsior: IIIb, n=6). The EDHF-mediated relaxation was significantly decreased in Group Ia (56.4+/-7.2% vs. 71.2+/-5.3%, P<0.05) and Ib (44.8+/-4.9% vs. 74.7+/-3.3%, P<0.05) but not in Ic. The sensitivity to BK was also significantly decreased (Ia: -7.51+/-0.14 vs. -7.76+/-0.12 log M, P<0.05; Ib: -7.36+/-0.09 vs. -7.60+/-0.09 logM, P<0.05). The resting membrane potential was depolarized in IIa (-44.3+/-1.9 mV, n=7, P<0.05) and IIb (-33.0+/-2.2 mV, n=6, P<0.05) compared with IIc (-57.1+/-1.5 mV, n=6). The EDHF-mediated hyperpolarization decreased significantly in IIa and IIb (3.4+/-0.3 and 3.0+/-0.2 vs. 6.3+/-0.5 mV, P<0.05) and partially restored in IIIa (5.0+/-0.2 vs. 3.4+/-0.3 mV, P<0.05) and IIIb (4.1+/-0.3 vs. 3.0+/-0.2 mV, P<0.05). Storage with Celsior and ST solutions reduces the EDHF-mediated endothelial function (hyperpolarization and associated relaxation) in porcine small resistance coronary arteries.

Hypoxia-Reoxygenation, St. Thomas Cardioplegic Solution, and Nicorandil on Endothelium-derived Hyperpolarizing Factor in Coronary Microarteries

We investigated effects of hypoxia-reoxygenation (H-R) with and without St. Thomas solution under clinically relevant temperatures and effects of nicorandil on endothelium-derived hyperpolarizing factor (EDHF)-mediated relaxation in porcine coronary microarteries. In a myograph, rings of porcine microarteries (diameter 200 to 450 microm) were subjected to hypoxia (PO2 < 5 mm Hg) for 30 minutes in Krebs at 37 degrees C, or for 60 minutes in Krebs and St. Thomas solution with or without nicorandil (0.1 microM) at 37 degrees C or 4 degrees C, followed by 30-minute reoxygenation. The EDHF-mediated relaxation by bradykinin (-10 to approximately -6 logM) with inhibitors of nitric oxide and prostacyclin was studied. The maximal EDHF-mediated relaxation was reduced after hypoxia for 30 minutes (59.9%% +/- 1.6% versus 81.2%% +/- 3.5%, p < 0.05) or 60 minutes (44.4% +/- 6.0% versus 82.7% +/- 7.4%, p < 0.001) in Krebs or St. Thomas (28.9% +/- 1.8% versus 78.1% +/- 3.0%, p < 0.001) at 37 degrees C and at 4 degrees C (Krebs: 49.3% +/- 3.0%, p < 0.001; ST: 43.1% +/- 2.6%, p < 0.001) and it was less in St. Thomas solution at 37 degrees C than at 4 degrees C (p < 0.001). The reduced relaxation was recovered by nicorandil (Krebs at 37 degrees C: 81.7% +/- 3.4%, p < 0.001; St. Thomas at 37 degrees C: 71.0% +/- 7.9%, p <0.001; St. Thomas at 4 degrees C: 85.3% +/- 3.3%, p < 0.001). We conclude that (1) H-R impairs EDHF-mediated relaxation in the coronary microarteries with more injury during prolonged H-R, and this can be partially eliminated by St. Thomas at 4 degrees C but not at 37 degrees C; and (2) as an additive, nicorandil may fully restore EDHF-mediated endothelial function after prolonged H-R.

Histidine–tryptophan–ketoglutarate solution maximally preserves endothelium-derived hyperpolarizing factor–mediated function during heart preservation: comparison with University of Wisconsin solution

Background The University of Wisconsin (UW) solution is used widely in heart preservation but has been demonstrated to be detrimental to the endothelial function. The present study compares the effect of histidine–tryptophan–ketoglutarate (HTK) and UW solutions on endothelium-derived hyperpolarizing factor (EDHF)-mediated function in porcine small coronary arteries. Methods An isometric force study was performed in a myograph and the membrane potential of a single smooth muscle cell was measured electrophysiologically. Small coronary arteries (diameter 457 ± 15 μm) were incubated with UW ( n = 8), HTK ( n = 7) or Krebs solution ( n = 15) at 4°C for 4 hours. After washout, in the presence of indomethacin (Indo; 7 μmol/liter), N G-nitro- l-arginine ( l-NNA; 300 μmol/liter) and oxyhemoglobin (HbO; 20 μmol/liter), bradykinin (BK; −10 to −6.5 log M)-induced relaxation was compared in U 46619 (−8 log M) pre-contraction. EDHF-mediated hyperpolarization was elicited by BK (−6.5 log M) in the presence of Indo, l-NNA and HbO. Results BK-induced, EDHF-mediated relaxation was reduced from 93.6 ± 2.8% to 79.7 ± 4.6% after UW preservation ( p = 0.01 by unpaired t-test and p = 0.005 by 2-way analysis of variance [ANOVA]), whereas HTK incubation did not decrease EDHF-mediated relaxation (87.0 ± 6.5%, p = 0.3 by unpaired t-test and p = 0.6 by 2-way ANOVA, compared with control, and p = 0.001 by 2-way ANOVA, compared with UW). EDHF-mediated hyperpolarization (10.3 ± 1.6 mV) was attenuated by UW exposure (3.4 ± 0.6 mV, [ p = 0.002] vs control), but not by HTK exposure (8.3 ± 1.1 mV, [ p = 0.3] vs control). Conclusions HTK is superior to UW solution in protecting EDHF-mediated endothelial function in porcine small coronary arteries. The present findings supports the use of HTK solution in heart preservation.

Effect of 11,12-epoxyeicosatrienoic acid as an additive to st. thomas’ cardioplegia and university of wisconsin solutions on endothelium-derived hyperpolarizing factor–mediated function in coronary microarteries: influence of temperature and time

Background We examined the effect of 11,12-epoxyeicosatrienoic acid (EET 11,12) added to St. Thomas’ Hospital (ST) solution or University of Wisconsin (UW) solution on endothelium-derived hyperpolarizing factor (EDHF)–mediated relaxation under clinically relevant temperature and exposure time. Methods Porcine coronary microarteries (200 to 450 μm) were incubated with Krebs’ solution (control), ST with or without EET 11,12 (300 nmol/L) at 22°C for 1 hour as well as at 4°C for 1 or 4 hours, and UW with or without EET 11,12 at 4°C for 4 hours. The EDHF-mediated relaxation was induced by bradykinin (−10 to approximately −6.5 log M) in the precontraction evoked by U 46619 (10 nmol/L) or U 46619 (1 nmol/L) plus endothelin-1 (6 nmol/L). Results The EDHF-mediated relaxation was reduced after exposure to UW (79.7% ± 4.6% versus 93.6% ± 2.8%, p = 0.01) at 4°C for 4 hours. One-hour exposure to ST under 22°C or 4°C decreased the relaxation (75.2% ± 7.6% versus 96.7% ± 1.6%, p < 0.05) or the sensitivity to bradykinin (−8.04 ± 0.15 versus −8.50 ± 0.20 log M, p < 0.05). The relaxation increased to 86.8% ± 5.3% by addition of EET 11,12 to ST (1 hour at 22°C, p < 0.05) but was unchanged when added to either ST or UW at 4°C for 1 or 4 hours. Conclusions As an additive to ST solution, EET 11,12 may partially restore EDHF-mediated endothelial function under moderate hypothermia but had no significant effect under profound hypothermia when added to either ST or UW solution. Further investigation is necessary to improve the effect.

Impaired EDHF‐Mediated Relaxation in Porcine Pulmonary Micro‐Arteries by Cold Storage with University of Wisconsin and Euro‐Collins Solutions

Background: Vascular endothelium plays a key role in regulation of vascular tone. Hyperkalemia has been demonstrated to impair the EDHF-mediated endothelial function in coronary circulation. University of Wisconsin (UW) and Eruo-collins (EC) solutions are used for organ preservation in transplantation surgery. The potassium concentration in UW or EC solutions is as high as 125 mmol/L or 115 mmol/L, respectively. This study was designed to examine whether hyperkalemia or storage with UW and EC solutions affects the relaxation mediated by EDHF in the porcine pulmonary micro-arteries. Methods: Porcine pulmonary micro-artery rings (diameter 200–450 μm) were studied in myograph (n = 8 in each group). After incubation with hyperkalemia (K+ 125 mmol/L, at 37° C), UW or EC solutions (at 4° C for 4 hours), EDHF-mediated relaxation induced by bradykinin (BK, −10 to −6.5 log M) in the presence of inhibitors for cyclooxygenase (Indomethacin, 7 μM), nitric oxide synthase (NG-nitro-L-arginine, 300 μM), and oxyhemoglobin (20 μM) was compared with control (Krebs' solution) in precontraction with U46619 (−7.5 log M). Results: The EDHF-mediated relaxation to BK was 69.6 ± 6.3% compared with 97.1 ± 1.7% (p= 0.003) in control (no inhibitors). After incubation with hyperkalemia, the relaxation significantly decreased (38.6 ± 3.0% vs. 59.1 ± 7.4%, p= 0.03). Storage with UW or EC solutions also significantly decreased the relaxation (49.3 ± 7.3% vs. 65.2 ± 3.5%, p= 0.04 and 51.9 ± 8.4% vs. 60.3 ± 6.1%, p= 0.02, respectively). Conclusions: In porcine pulmonary micro-arteries, exposure to hyperkalemia or storage with UW or EC solutions at 4°C for 4 hours impairs the EDHF-mediated endothelial function. The clinical significance of this effect should be further studied.

Procaine in Cardioplegia: Does It Affect the Endothelial Function?

Objective: Cardioplegic solutions are widely used in cardiac surgery and hyperkelemia in cardioplegia has been demonstrated to impair the endothelium-derived hyperpolarizing factor (EDHF)-mediated endothelial function. The present study examined the effect of procaine in St. Thomas Hospital Cardioplegia on the EDHF-mediated response in porcine coronary arteries. Methods: Isometric force study: Porcine coronary micro-arteries were studied in a myograph. Two rings taken from the same artery (diameter 200–450 μm, n = 8) were incubated with Kreb's solution as control or Kreb's solution plus procaine (1 mM) at 37 °C for 1 h, respectively. The EDHF-mediated relaxation was induced by bradykinin (BK, −10 ∼−6.5 log M) in the presence of indomethacin (Indo, 7 μM), NG-nitro-L-arginine (L-NNA, 300 μM), and hemoglobin (HbO, 20 μM) after U46619-precontraction (−8 log M). Electrophysiological study: The membrane potential of a single smooth muscle cell in coronary arteries was measured by a microelectrode after superfusion with Kreb's solution or Kreb's containing procaine (1 mM) for 1 h. Results: Procaine had little effect on the resting force of porcine coronary micro-arteries (0.94 ± 0.74 mN vs. 0.67 ± 0.23 mN in control, P > 0.05) and did not alter the U46619-induced precontraction (10.7 ± 1.7 mN vs. 12.0 ± 1.7 mN, P > 0.05). The BK-induced, EDHF-mediated relaxation was increased by the treatment with procaine with the EC50 shifted leftward (97.3 ± 0.6% vs. 83.0 ± 5.1% at −7 log M and 99.4 ± 0.6% vs. 96.7 ± 1.6% at −6.5 log M, P 0.05) and decreased the BK-induced hyperpolarization from −70.3 ± 0.4 mV to −68.0 ± 0.8 mV (−7 log M, P < 0.05) and from −72.3 ± 0.7 mV to −68.8 ± 0.8 mV (−6.5 log M, P < 0.01). Conclusions: In the coronary arteries, procaine has depolarizing effect but it enhances the EDHF-mediated relaxation. Therefore, addition of procaine in cardioplegia may preserve the EDHF-mediated endothelial function.

Effect and mechanism of cardioplegic arrest on the coronary endothelium-smooth muscle interaction.

1. During cardiac surgery, the heart is arrested and protected by hyperkalaemic cardioplegia. The coronary endothelium may be damaged by ischaemia-reperfusion and cardioplegia. Subsequently, this may affect cardiac function immediately after cardiac surgery and cause mortality and morbidity. 2. We investigated coronary endothelium-smooth muscle interaction after exposure to depolarizing (hyperkalaemic; K+ 20 or 50 mmol/L) and hyperpolarizing (the K+ channel opener aprikalim) cardioplegia and organ preservation solution (University of Wisconsin (UW) solution). Endothelium-dependent relaxation and hyperpolarization of the coronary smooth muscle were studied in the porcine and human large conductance and micro-coronary arteries. Intracellular free calcium concentration in endothelial cells was also measured. 3. The endothelium-derived hyperpolarizing factor (EDHF)-mediated relaxation to A23187, bradykinin, and substance P in arteries contracted by either U46619 (10 nmol/L) or K+ (25 mmol/L) was reduced after exposure to either high K+ or UW solution, but was maximally preserved after exposure to aprikalim. The hyperpolarization of the membrane potential in response to the above endothelium-derived relaxing factor stimuli was also reduced by exposure to depolarizing cardioplegia. Studies in microcoronary arteries are in accordance with findings in large arteries. The intracellular free calcium concentration remained unchanged after exposure to hyperkalaemia. 4. We concluded that: (i) during cardiac surgery, the function of coronary circulation may be changed due to exposure to depolarizing cardioplegia or preservation solutions; (ii) the functional change in the coronary circulation is related to the altered interaction between the endothelium and smooth muscle; (iii) depolarizing (hyperkalaemia) cardioplegia or hyperkalaemic organ preservation solutions affect endothelium-smooth muscle interaction through the EDHF pathway; (iv) EDHF relaxes the porcine large and microcoronary arteries through multiple K+ channels; and (v) that hyperpolarizing vasodilators (K+ channel openers) may protect EDHF-mediated endothelial function when used as cardioplegia.

Action and metabolism of bradykinin in dog lung.

ArticleAction and metabolism of bradykinin in dog lung.B W Levine, R C Talamo, and H KazemiB W Levine, R C Talamo, and H KazemiPublished Online:01 Jun 1973https://doi.org/10.1152/jappl.1973.34.6.821MoreSectionsPDF (2 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInEmailWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformationCited ByLung Circulation15 March 2016Role of NO and EDHF-mediated endothelial function in the porcine pulmonary circulation: Comparison between pulmonary artery and veinVascular Pharmacology, Vol. 44, No. 3Bradykinin causes hypotension by activating pulmonary sympathetic afferents in the rabbitY. Wang, G. Soukhova, M. Proctor, J. Walker, and J. Yu1 July 2003 | Journal of Applied Physiology, Vol. 95, No. 1Evidence for specific regional patterns of responses to different vasoconstrictors and vasodilators in sheep isolated pulmonary arteries and veins10 February 2009 | British Journal of Pharmacology, Vol. 121, No. 3Cyclophilin-facilitated bradykinin inactivation in the perfused rat lungBiochemical Pharmacology, Vol. 50, No. 12Beneficial Effects of a Bradykinin Antagonist in a Model of Gram-Negative SepsisThe Journal of Trauma: Injury, Infection, and Critical Care, Vol. 39, No. 1Afferent pathways involved in reflex regulation of airway smooth musclePharmacology & Therapeutics, Vol. 42, No. 1The kallikrein kinin system in pulmonary lavage fluid of reserpinized ratsPharmacological Research Communications, Vol. 20, No. 8Attenuation of arterial blood pressure fall in endotoxin shock in the rat using the competitive bradykinin antagonist Lys-Lys-[Hyp2, Thi5,8, DPhe7]-Bk (B4148)19 July 2012 | British Journal of Pharmacology, Vol. 94, No. 2Cellular and humoral mediators of pulmonary edemaLung, Vol. 163, No. 1Afferent vagal C fibre innervation of the lungs and airways and its functional significance21 June 2005The adult respiratory distress syndromeDisease-a-Month, Vol. 27, No. 4Method for Measurement of Human Urinary Kininase Activity22 October 2012Effects of Kinins on Organ SystemsKininasesBradykinin RadioimmunoassayRole of prostaglandins in alveolar hypoxic vasoconstrictionRespiration Physiology, Vol. 29, No. 2Plasma Factors: The Hageman-Factor-Dependent Pathways and the Complement SequenceBRADYKININASE AND CONVERTING ENZYME IN LUNG More from this issue > Volume 34Issue 6June 1973Pages 821-6 https://doi.org/10.1152/jappl.1973.34.6.821PubMed4711592History Published online 1 June 1973 Published in print 1 June 1973 Metrics