CO modulates pulmonary vascular response to acute hypoxia: relation to endothelin

2004 ◽  
Vol 286 (1) ◽  
pp. H137-H144 ◽  
Author(s):  
Fan Zhang ◽  
Jun Ichi Kaide ◽  
LiMing Yang ◽  
Houli Jiang ◽  
Shuo Quan ◽  
...  
Keyword(s):  
Pulmonary Arterial Pressure ◽  
Acute Hypoxia ◽  
Isometric Tension ◽  
Vascular Response ◽  
Tension Development ◽  
Pulmonary Vasoconstriction ◽  
Pulmonary Arterial ◽  
Hypoxic Gas Mixture ◽  
Concentration Response Curve ◽  
Krebs Buffer

Pulmonary intralobar arteries express heme oxygenase (HO)-1 and -2 and release carbon monoxide (CO) during incubation in Krebs buffer. Acute hypoxia elicits isometric tension development (0.77 ± 0.06 mN/mm) in pulmonary vascular rings treated with 15 μmol/l chromium mesoporphyrin (CrMP), an inhibitor of HO-dependent CO synthesis, but has no effect in untreated vessels. Acute hypoxia also induces contraction of pulmonary vessels taken from rats injected with HO-2 antisense oligodeoxynucleotides (ODN), which decrease pulmonary HO-2 vascular expression and CO release. Hypoxia-induced contraction of vessels treated with CrMP is attenuated ( P < 0.05) by endothelium removal, by CO (1–100 μmol/l) in the bathing buffer, and by endothelin-1 (ET-1) receptor blockade with L-754142 (10 μmol/l). CrMP increases ET-1 levels in pulmonary intralobar arteries, particularly during incubation in hypooxygenated media. CrMP also causes a leftward shift in the concentration-response curve to ET-1, which is offset by exogenous CO. In anesthetized rats, pretreatment with CrMP (40 μmol/kg iv) intensifies the elevation of pulmonary artery pressure elicited by breathing a hypoxic gas mixture. However, acute hypoxia does not elicit augmentation of pulmonary arterial pressure in rats pretreated concurrently with CrMP and the ET-1 receptor antagonist L-745142 (15 mg/kg iv). These data suggest that a product of HO activity, most likely CO, inhibits hypoxia-induced pulmonary vasoconstriction by reducing ET-1 vascular levels and sensitivity.

Carbon Monoxide Is an Inhibitory Regulator of Hypoxia-Induced Contraction of Small Pulmonary Arteries.

Hypertension ◽  
2000 ◽  
Vol 36 (suppl_1) ◽  
pp. 699-699
Author(s):  
Fan Zhang ◽  
Jun-Ichi Kaide ◽  
Alberto Nasjletti
Keyword(s):  
Carbon Monoxide ◽  
Pulmonary Arteries ◽  
Systemic Circulation ◽  
Isometric Tension ◽  
Endothelin Receptors ◽  
Small Arteries ◽  
Pulmonary Vasoconstriction ◽  
Vascular Responsiveness ◽  
Pulmonary Arterial ◽  
Krebs Buffer

P36 Hypoxia elicits pulmonary vasoconstriction, endothelin production and expression of heme oxygenase (HO)-1. In small arteries and arterioles of the systemic circulation, HO catalyzes synthesis of carbon monoxide (CO) which attenuates vascular responsiveness to constrictor stimuli. This study examines the hypothesis that HO-derived CO inhibits constrictor responsiveness to hypoxia in rat pulmonary arterial vessels (PA). Experiments were conducted on rings of large PA (ID=1051±78 μm) and small PA (ID=153±12μm) bathed in Krebs buffer and mounted on a wire-myograph for measurement of isometric tension (IT). Exposure to hypooxygenated buffer (PO 2 15 mmHg) elicited minimal increase of IT in small PA (0.026±0.008 mN/mm) but in preparations bathed in buffer containing chromium mesoporphyrin (30 μM, CrMP), an inhibitor of HO-dependent CO synthesis, hypoxia elicited a much more intense increase of IT (0.77±0.06 mN/mm, P<0.05). Hypoxia-induced contraction of large PA also was magnified by pretreatment of the vessels with CrMP (from 0.030±0.007 to 0.077±0.016, P<0.05) but the intensity of the response was less than in similarly treated small PA. In small PA treated with CrMP, hypoxia-induced contractions were attenuated by exogenous CO (10 μM) (from 0.77±0.06 to 0.15±0.05 mN/mm); contraction also were reduced in preparations denuded of endothelium (0.27±0.09 versus 0.77±0.06 mN/mm). Hypoxia-induced contractions of endothelium-intact small PA bathed in buffer containing CrMP were greatly inhibited by pretreatment with L754,142 (10 μM), a blocker of endothelin receptors. These data suggest that endogenous CO is an inhibitory regulator of hypoxia-induced contractions in small PA. This action of CO may reflect inhibition of hypoxia-induced endothelin production or of endothelin-induced vascular contraction.

Hypoxia-induced alterations of norepinephrine vascular reactivity in isolated perfused cat lung

1987 ◽  
Vol 63 (3) ◽  
pp. 982-987 ◽  
Author(s):  
M. Cutaia ◽  
P. Friedrich
Keyword(s):  
Arterial Pressure ◽  
Vascular Resistance ◽  
Significant Relationship ◽  
Vascular Reactivity ◽  
Pulmonary Arterial Pressure ◽  
Pressor Response ◽  
Acute Hypoxia ◽  
Beta Blockade ◽  
Vascular Response ◽  
Pulmonary Arterial

Past work in the isolated perfused cat lung has shown that acute hypoxia (H) changes the response to norepinephrine (NE) from vasoconstriction to vasodilation but has no effect on the response to serotonin (S). These results could be related to the increase in pulmonary arterial pressure or vascular resistance during the hypoxic pressor response or a direct effect of H. We addressed this question, in the same preparation, by comparing responses to NE under four conditions in each experimental animal (n = 12): 1) NE infused during normoxia; 2) NE infused after vascular resistance (Rpv) was increased with serotonin; 3) NE infused after Rpv was increased by H; 4) NE infused after lobar pressure was raised by an increase in flow (P/F). PO2 values during H were varied (27–56 Torr). S and H produced a 137 +/- 35 and 43 +/- 8% delta Rpv increase in lobar vascular resistance, respectively. P/F increased lobar pressure 91 +/- 10%. Only NE infusion during H demonstrated significant differences in lobar pressure and Rpv compared with control normoxic periods. There was no correlation between responses to NE during S, H, and P/F and degree to which each stimulus increased Rpv or lobar pressure (r = 0.003, 0.28, 0.24). A significant relationship between response to NE during H vs. PO2 during H was observed (r = 0.78; P less than 0.001). In a subset of animals, we repeated the infusion of NE during H and P/F post-beta-blockade. The decrease in vascular response to NE during H and the correlation of PO2 with NE response were abolished (n = 7).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetazolamide prevents hypoxic pulmonary vasoconstriction in conscious dogs

2004 ◽  
Vol 97 (2) ◽  
pp. 515-521 ◽  
Author(s):  
Claudia Höhne ◽  
Martin O. Krebs ◽  
Manuela Seiferheld ◽  
Willehad Boemke ◽  
Gabriele Kaczmarczyk ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Pulmonary Vascular Resistance ◽  
Vascular Resistance ◽  
Pulmonary Arterial Pressure ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Acute Hypoxia ◽  
Conscious Dogs ◽  
Mean Pulmonary Arterial Pressure ◽  
Pulmonary Vasoconstriction ◽  
Pulmonary Arterial

Acute hypoxia increases pulmonary arterial pressure and vascular resistance. Previous studies in isolated smooth muscle and perfused lungs have shown that carbonic anhydrase (CA) inhibition reduces the speed and magnitude of hypoxic pulmonary vasoconstriction (HPV). We studied whether CA inhibition by acetazolamide (Acz) is able to prevent HPV in the unanesthetized animal. Ten chronically tracheotomized, conscious dogs were investigated in three protocols. In all protocols, the dogs breathed 21% O2 for the first hour and then 8 or 10% O2 for the next 4 h spontaneously via a ventilator circuit. The protocols were as follows: protocol 1: controls given no Acz, inspired O2 fraction (FiO2) = 0.10; protocol 2: Acz infused intravenously (250-mg bolus, followed by 167 μg·kg−1·min−1 continuously), FiO2 = 0.10; protocol 3: Acz given as above, but with FiO2 reduced to 0.08 to match the arterial Po2 (PaO2) observed during hypoxia in controls. PaO2 was 37 Torr during hypoxia in controls, mean pulmonary arterial pressure increased from 17 ± 1 to 23 ± 1 mmHg, and pulmonary vascular resistance increased from 464 ± 26 to 679 ± 40 dyn·s−1·cm−5 ( P < 0.05). In both Acz groups, mean pulmonary arterial pressure was 15 ± 1 mmHg, and pulmonary vascular resistance ranged between 420 and 440 dyn·s−1·cm−5. These values did not change during hypoxia. In dogs given Acz at 10% O2, the arterial PaO2 was 50 Torr owing to hyperventilation, whereas in those breathing 8% O2 the PaO2 was 37 Torr, equivalent to controls. In conclusion, Acz prevents HPV in conscious spontaneously breathing dogs. The effect is not due to Acz-induced hyperventilation and higher alveolar Po2, nor to changes in plasma endothelin-1, angiotensin-II, or potassium, and HPV suppression occurs despite the systemic acidosis with CA inhibition.

Regional pulmonary blood flow during 96 hours of hypoxia in conscious sheep

1986 ◽  
Vol 61 (6) ◽  
pp. 2136-2143 ◽  
Author(s):  
D. C. Curran-Everett ◽  
K. McAndrews ◽  
J. A. Krasney
Keyword(s):  
Blood Flow ◽  
Arterial Pressure ◽  
Pulmonary Blood Flow ◽  
Pulmonary Arterial Pressure ◽  
Pressor Response ◽  
Superior Vena ◽  
Acute Hypoxia ◽  
Vena Cava ◽  
Normobaric Hypoxia ◽  
Pulmonary Arterial

The effects of acute hypoxia on regional pulmonary perfusion have been studied previously in anesthetized, artificially ventilated sheep (J. Appl. Physiol. 56: 338–342, 1984). That study indicated that a rise in pulmonary arterial pressure was associated with a shift of pulmonary blood flow toward dorsal (nondependent) areas of the lung. This study examined the relationship between the pulmonary arterial pressor response and regional pulmonary blood flow in five conscious, standing ewes during 96 h of normobaric hypoxia. The sheep were made hypoxic by N2 dilution in an environmental chamber [arterial O2 tension (PaO2) = 37–42 Torr, arterial CO2 tension (PaCO2) = 25–30 Torr]. Regional pulmonary blood flow was calculated by injecting 15-micron radiolabeled microspheres into the superior vena cava during normoxia and at 24-h intervals of hypoxia. Pulmonary arterial pressure increased from 12 Torr during normoxia to 19–22 Torr throughout hypoxia (alpha less than 0.049). Pulmonary blood flow, expressed as %QCO or ml X min-1 X g-1, did not shift among dorsal and ventral regions during hypoxia (alpha greater than 0.25); nor were there interlobar shifts of blood flow (alpha greater than 0.10). These data suggest that conscious, standing sheep do not demonstrate a shift in pulmonary blood flow during 96 h of normobaric hypoxia even though pulmonary arterial pressure rises 7–10 Torr. We question whether global hypoxic pulmonary vasoconstriction is, by itself, beneficial to the sheep.

Enhancement of the pulmonary vasoconstriction reaction to alveolar hypoxia in systemic high blood pressure

1989 ◽  
Vol 76 (6) ◽  
pp. 589-594 ◽  
Author(s):  
Maurizio D. Guazzi ◽  
Marco Berti ◽  
Elisabetta Doria ◽  
Cesare Fiorentini ◽  
Claudia Galli ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Smooth Muscle ◽  
Arterial Pressure ◽  
High Blood Pressure ◽  
Pulmonary Arterial Pressure ◽  
Systemic Hypertension ◽  
Pulmonary Vasoconstriction ◽  
Arteriolar Resistance ◽  
Alveolar Hypoxia ◽  
Pulmonary Arterial

1. In systemic hypertension the pulmonary vessels show an excessive tone at rest and hyper-react to adrenoceptor stimulation. Alterations in Ca2+ handling by the vascular smooth muscle cells seem to underlie these disorders. Alveolar hypoxia also constricts pulmonary arteries, increasing the intracellular Ca2+ availability for smooth muscle contraction. This suggests the hypothesis that hypoxic pulmonary vasoconstriction depends on similar biochemical disorders, and that the response to the hypoxic stimulus may be emphasized in high blood pressure. 2. In 21 hypertensive and 10 normotensive men, pulmonary arterial pressure and arteriolar resistance have been evaluated during air respiration and after 15 min of breathing 17, 15 and 12% oxygen in nitrogen. Curves relating changes in pulmonary arterial pressure and arteriolar resistance to the oxygen content of inspired gas had a similar configuration in the two populations, but in hypertension were steeper and significantly shifted to the left of those in normotension, reflecting a lower threshold and an enhanced vasoconstrictor reactivity. 3. This pattern was not related to differences in severity of the hypoxic stimulus, degree of hypocapnia and respiratory alkalosis induced by hypoxia, and plasma catecholamines. 4. The association of high blood pressure with enhanced pulmonary vasoreactivity to alveolar hypoxia could have clinical implications in patients who are chronically hypoxic and have systemic hypertension.

Inhibition of hypoxic pulmonary vasoconstriction by antagonists of store-operated Ca2+ and nonselective cation channels

2005 ◽  
Vol 289 (1) ◽  
pp. L5-L13 ◽  
Author(s):  
Letitia Weigand ◽  
Joshua Foxson ◽  
Jian Wang ◽  
Larissa A. Shimoda ◽  
J. T. Sylvester
Keyword(s):  
Hypoxic Pulmonary Vasoconstriction ◽  
Acute Hypoxia ◽  
Pulmonary Arteries ◽  
Cation Channels ◽  
Pulmonary Vasoconstriction ◽  
Nonselective Cation Channels ◽  
Pressor Responses ◽  
Intracellular Ca ◽  
Pulmonary Arterial

Previous studies indicated that acute hypoxia increased intracellular Ca2+ concentration ([Ca2+]i), Ca2+ influx, and capacitative Ca2+ entry (CCE) through store-operated Ca2+ channels (SOCC) in smooth muscle cells from distal pulmonary arteries (PASMC), which are thought to be a major locus of hypoxic pulmonary vasoconstriction (HPV). Moreover, these effects were blocked by Ca2+-free conditions and antagonists of SOCC and nonselective cation channels (NSCC). To test the hypothesis that in vivo HPV requires CCE, we measured the effects of SOCC/NSCC antagonists (SKF-96365, NiCl2, and LaCl3) on pulmonary arterial pressor responses to 2% O2 and high-KCl concentrations in isolated rat lungs. At concentrations that blocked CCE and [Ca2+]i responses to hypoxia in PASMC, SKF-96365 and NiCl2 prevented and reversed HPV but did not alter pressor responses to KCl. At 10 μM, LaCl3 had similar effects, but higher concentrations (30 and 100 μM) caused vasoconstriction during normoxia and potentiated HPV, indicating actions other than SOCC blockade. Ca2+-free perfusate and the voltage-operated Ca2+ channel (VOCC) antagonist nifedipine were potent inhibitors of pressor responses to both hypoxia and KCl. We conclude that HPV required influx of Ca2+ through both SOCC and VOCC. This dual requirement and virtual abolition of HPV by either SOCC or VOCC antagonists suggests that neither channel provided enough Ca2+ on its own to trigger PASMC contraction and/or that during hypoxia, SOCC-dependent depolarization caused secondary activation of VOCC.

Effect of hypoxia on pulmonary artery pressure of dogs

1964 ◽  
Vol 207 (6) ◽  
pp. 1314-1318 ◽  
Author(s):  
Benson R. Wilcox ◽  
W. Gerald Austen ◽  
Harvey W. Bender
Keyword(s):  
Pulmonary Artery ◽  
Arterial Pressure ◽  
Pulmonary Artery Pressure ◽  
Pulmonary Arterial Pressure ◽  
Venous Pressure ◽  
Artery Pressure ◽  
Pulmonary Vasoconstriction ◽  
Systemic Hypoxia ◽  
Pump Output ◽  
Pulmonary Arterial

The mechanism by which the pulmonary artery pressure rises in response to hypoxia has never been clearly demonstrated. This problem was reinvestigated in experiments utilizing separate pulmonary and systemic perfusion systems. These vascular beds were perfused in such a fashion that a change in pulmonary artery pressure could only result from changes in vasomotor tone. Alveolar-pulmonary vein hypoxia was usually associated with a slight fall in pulmonary artery pressure. Systemic hypoxia resulted in elevation of pulmonary arterial pressure in 10 of the 12 animals tested with a constant-flow and constant-pulmonary venous pressure. In addition, all animals with systemic desaturation showed an increased venous return. When the "cardiac output" (pump output) was increased to match this return, the elevation in pulmonary artery pressure increased. It was concluded that the pulmonary arterial pressure elevation seen with hypoxia is the result of active pulmonary vasoconstriction coupled with an increased pulmonary blood flow.

Role of PKC, tyrosine kinases, and Rho kinase in α-adrenoreceptor-mediated PASM contraction

2002 ◽  
Vol 283 (5) ◽  
pp. L1051-L1064 ◽  
Author(s):  
Derek S. Damron ◽  
Noriaki Kanaya ◽  
Yasuyuki Homma ◽  
Si-Oh Kim ◽  
Paul A. Murray
Keyword(s):  
Tyrosine Kinases ◽  
Rho Kinase ◽  
Isometric Tension ◽  
Vasomotor Tone ◽  
Tension Development ◽  
Pulmonary Arterial ◽  
Pulmonary Artery Smooth Muscle ◽  
Sensitizing Effect ◽  
Multiple Signaling

Our objectives were to identify the relative contributions of intracellular free Ca2+ concentration ([Ca2+]i) and myofilament Ca2+ sensitivity in the pulmonary artery smooth muscle (PASM) contractile response to the α-adrenoreceptor agonist phenylephrine (PE) and to assess the role of PKC, tyrosine kinases (TK), and Rho kinase (ROK) in that response. Our hypothesis was that multiple signaling pathways are involved in the regulation of [Ca2+]i, myofilament Ca2+sensitization, and vasomotor tone in response to α-adrenoreceptor stimulation of PASM. Simultaneous measurement of [Ca2+]i and isometric tension was performed in isolated canine pulmonary arterial strips loaded with fura 2-AM. PE-induced tension development was due to sarcolemmal Ca2+influx, Ca2+ release from inositol 1,4,5-trisphosphate-dependent sarcoplasmic reticulum Ca2+stores, and myofilament Ca2+ sensitization. Inhibition of either PKC or TK partially attenuated the sarcolemmal Ca2+influx component and the myofilament Ca2+ sensitizing effect of PE. Combined inhibition of PKC and TK did not have an additive attenuating effect on PE-induced Ca2+sensitization. ROK inhibition slightly decreased [Ca2+]i but completely inhibited myofilament Ca2+ sensitization. These results indicate that PKC and TK activation positively regulate sarcolemmal Ca2+ influx in response to α-adrenoreceptor stimulation in PASM but have relatively minor effects on myofilament Ca2+ sensitivity. ROK is the predominant pathway mediating PE-induced myofilament Ca2+sensitization.

Does leukotriene C4 mediate hypoxic vasoconstriction in isolated ferret lungs?

1990 ◽  
Vol 68 (1) ◽  
pp. 253-259 ◽  
Author(s):  
C. M. Tseng ◽  
M. McGeady ◽  
T. Privett ◽  
A. Dunn ◽  
J. T. Sylvester
Keyword(s):  
Pulmonary Arterial Pressure ◽  
Pressor Response ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Physiological Salt Solution ◽  
Leukotriene C4 ◽  
Prostaglandin F2 Alpha ◽  
Pulmonary Vasoconstriction ◽  
Vasoconstrictor Response ◽  
Hypoxic Vasoconstriction ◽  
Pulmonary Arterial

To evaluate leukotriene (LT) C4 as a mediator of hypoxic pulmonary vasoconstriction, we examined the effects of FPL55712, a putative LT antagonist, and indomethacin, a cyclooxygenase inhibitor, on vasopressor responses to LTC4 and hypoxia (inspired O2 tension = 25 Torr) in isolated ferret lungs perfused with a constant flow (50 ml.kg-1.min-1). Pulmonary arterial injections of LTC4 caused dose-related increases in pulmonary arterial pressure during perfusion with physiological salt solution containing Ficoll (4 g/dl). FPL55712 caused concentration-related inhibition of the pressor response to LTC4 (0.6 micrograms). Although 10 micrograms/ml FPL55712 inhibited the LTC4 pressor response by 61%, it did not alter the response to hypoxia. At 100 microgram/ml, FPL55712 inhibited the responses to LTC4 and hypoxia by 73 and 71%, respectively, but also attenuated the vasoconstrictor responses to prostaglandin F2 alpha (78% at 8 micrograms), phenylephrine (68% at 100 micrograms), and KCl (51% at 40 mM). At 0.5 microgram/ml, indomethacin significantly attenuated the pressor response to arachidonic acid but did not alter responses to LTC4 or hypoxia. These results suggest that in isolated ferret lungs 1) the vasoconstrictor response to LTC4 did not depend on release of cyclooxygenase products and 2) LTC4 did not mediate hypoxic vasoconstriction.

Hypoxic pulmonary hypertension of the calf with denervation of the lungs

1964 ◽  
Vol 19 (5) ◽  
pp. 976-980 ◽  
Author(s):  
John T. Reeves ◽  
James E. Leathers
Keyword(s):  
Spinal Cord ◽  
Central Nervous System ◽  
Nervous System ◽  
Arterial Pressure ◽  
Spinal Anesthesia ◽  
Pulmonary Arterial Pressure ◽  
Acute Hypoxia ◽  
Pressure Rise ◽  
The Central Nervous System ◽  
Pulmonary Arterial

Transection of the spinal cord at the level of C2, spinal anesthesia, and/or bilateral vagotomy were done in 11 healthy young male calves. These procedures did not block the pulmonary arterial pressure rise with 12 or 9% oxygen, but they did block the increase in heart rate and systemic arterial pressure which accompanied hypoxia when the central nervous system was intact. The central nervous system, therefore, appeared to mediate the response to acute hypoxia of the systemic circulation, but not the pulmonary arterial pressure rise. hypoxia; pulmonary circulation; spinal cord section; spinal anesthesia; vagotomy Submitted on February 19, 1964

Sign in / Sign up

Export Citation Format

Share Document