Pulmonary and systemic vascular effects of SRS-A blockade in conscious lambs

1985 ◽  
Vol 249 (5) ◽  
pp. H968-H973
Author(s):  
T. J. Kulik ◽  
R. K. Schutjer ◽  
D. F. Howland ◽  
J. E. Lock
Keyword(s):  
Arterial Pressure ◽  
Systemic Vascular Resistance ◽  
Vascular Resistance ◽  
Pulmonary Arterial Pressure ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Systemic Resistance ◽  
Adrenergic Blockade ◽  
Vascular Effects ◽  
Pulmonary Vasoconstriction ◽  
Pulmonary Arterial

There is preliminary evidence suggesting that hypoxic pulmonary vasoconstriction may be mediated by slow-reacting substance of anaphylaxis (SRS-A), which is comprised of leukotrienes C4, D4, and E4. We studied the effects of the SRS-A antagonist FPL 57231 (FPL) on the hypoxic pulmonary vasoconstrictor response and on systemic vascular resistance in awake, chronically instrumented young lambs. Two other studies were performed to ascertain whether FPL's vasodilation was specific for hypoxic pulmonary vasoconstriction: the effect of FPL infusion in pulmonary and systemic vascular resistance was measured in six normoxic lambs, and the effect of FPL on 5-hydroxytryptamine (5-HT)-mediated vasoconstriction was determined. In seven lambs, mean pulmonary arterial pressure was 21 mmHg in room air and 28 mmHg in hypoxia (Po2 = 43 Torr). During hypoxia, FPL infusion (2 mg X kg-1 X min-1) reversibly decreased pulmonary arterial pressure to 15 mmHg; pulmonary arteriolar resistance also fell below normoxia levels with FPL. FPL also caused a fall in aortic pressure and systemic vascular resistance in these hypoxic lambs, but the decrease in systemic resistance was less than the fall in pulmonary resistance. beta-Adrenergic blockade using propranolol (1 mg/kg) did not affect the pulmonary vasodilation caused by FPL. In six normoxic lambs, FPL infusion also significantly decreased pulmonary and systemic vascular resistance (29% in each case). These data are consistent with the idea that leukotrienes may be involved in adjusting both pulmonary and systemic vascular tone, but further work is necessary to establish whether FPL's vasodilation is mediated via its leukotriene antagonism or is a nonspecific effect of FPL.

Pulmonary arterial pressure-flow plots in dogs: effects of isoflurane and nitroprusside

1987 ◽  
Vol 63 (3) ◽  
pp. 969-977 ◽  
Author(s):  
R. Naeije ◽  
P. Lejeune ◽  
M. Leeman ◽  
C. Melot ◽  
T. Deloof
Keyword(s):  
Arterial Pressure ◽  
Pulmonary Arterial Pressure ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Arachidonic Acid Metabolism ◽  
Minimal Alveolar Concentration ◽  
Vascular Effects ◽  
Pulmonary Vasoconstriction ◽  
Anesthetized Dogs ◽  
Pulmonary Arterial ◽  
End Tidal

We investigated the effects of nitroprusside and isoflurane on multipoint pulmonary arterial pressure (PAP)/cardiac index (Q) plots in pentobarbital sodium-anesthetized dogs ventilated alternatively in hyperoxia (fraction of inspired O2, FIO2, 0.4) and hypoxia (FIO2 0.1). Over the entire range of Q studied, 2–5 l.min-1.m-2, hypoxia increased PAP in 16 dogs (“responders”) and did not affect PAP in 16 other dogs (“nonresponders”). A hypoxic pulmonary vasoconstriction (HPV) was restored in the nonresponders by intravenous administration of 1 g of acetylsalicylic acid (ASA). Nitroprusside (5 micrograms.kg-1.min-1) inhibited HPV in responders (n = 8) and nonresponders treated with ASA (n = 8). End-tidal 1.41% isoflurane (a minimal alveolar concentration equal to one for dogs) did not affect HPV in responders (n = 8) and nonresponders treated with ASA (n = 8). In the latter group isoflurane increased PAP at the highest Q studied (3–5 l.min-1.m-2) in hyperoxia and hypoxia. In a final group of eight dogs with Q kept constant, PAP remained unchanged during two consecutive sequences of alternated 30-min periods (maximum time to generate a PAP/Q plot) successively at FIO2 0.4 and 0.1, and the hypoxia-induced increase in PAP was reproducible. Thus the present experimental model appeared suitable for the study of the effects of hypoxia and drugs on pulmonary vascular tone of intact dogs. At the given doses HPV was inhibited by nitroprusside and not affected by isoflurane. Products of arachidonic acid metabolism possibly could be implicated in the pulmonary vascular effects of isoflurane.

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.

Inhaled nitric oxide partially reverses hypoxic pulmonary vasoconstriction in the dog

1994 ◽  
Vol 76 (3) ◽  
pp. 1350-1355 ◽  
Author(s):  
J. A. Romand ◽  
M. R. Pinsky ◽  
L. Firestone ◽  
H. A. Zar ◽  
J. R. Lancaster
Keyword(s):  
Nitric Oxide ◽  
Arterial Pressure ◽  
Pulmonary Vascular Resistance ◽  
Vascular Resistance ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Canine Model ◽  
Systemic Arterial Pressure ◽  
Vasomotor Tone ◽  
Pulmonary Vasoconstriction ◽  
Pulmonary Arterial

Nitric oxide (NO) inhaled during a hypoxia-induced increase in pulmonary vasomotor tone decreases pulmonary arterial pressure (Ppa). We conducted this study to better characterize the hemodynamic effects induced by NO inhalation during hypoxic pulmonary vasoconstriction in 11 anesthetized ventilated dogs. Arterial and venous systemic and pulmonary pressures and aortic flow probe-derived cardiac output were recorded, and nitrosylhemoglobin (NO-Hb) and methemoglobin (MetHb) were measured. The effects of 5 min of NO inhalation at 0, 17, 28, 47, and 0 ppm during hyperoxia (inspiratory fraction of O2 = 0.5) and hypoxia (inspiratory fraction of O2 = 0.16) were observed. NO inhalation has no measurable effects during hyperoxia. Hypoxia induced an increase in Ppa that reached plateau levels after 5 min. Exposure to 28 and 47 ppm NO induced an immediate (< 30 s) decrease in Ppa and calculated pulmonary vascular resistance (P < 0.05 each) but did not return either to baseline hyperoxic values. Increasing the concentration of NO to 74 and 145 ppm in two dogs during hypoxia did not induce any further decreases in Ppa. Reversing hypoxia while NO remained at 47 ppm further decreased Ppa and pulmonary vascular resistance to baseline values. NO inhalation did not induce decreases in systemic arterial pressure. MetHb remained low, and NO-Hb was unmeasurable. We concluded that NO inhalation only partially reversed hypoxia-induced increases in pulmonary vasomotor tone in this canine model. These effects are immediate and selective to the pulmonary circulation.

Rho kinase and Ca2+ entry mediate increased pulmonary and systemic vascular resistance in l-NAME-treated rats

2007 ◽  
Vol 293 (5) ◽  
pp. L1306-L1313 ◽  
Author(s):  
Jasdeep S. Dhaliwal ◽  
David B. Casey ◽  
Anthony J. Greco ◽  
Adeleke M. Badejo ◽  
Thomas B. Gallen ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Arterial Pressure ◽  
Systemic Vascular Resistance ◽  
Vascular Resistance ◽  
Pulmonary Arterial Pressure ◽  
Rho Kinase ◽  
Systemic Arterial Pressure ◽  
Intravenous Injections ◽  
Pulmonary Arterial ◽  
Dose Dependent

The small GTP-binding protein and its downstream effector Rho kinase play an important role in the regulation of vasoconstrictor tone. Rho kinase activation maintains increased pulmonary vascular tone and mediates the vasoconstrictor response to nitric oxide (NO) synthesis inhibition in chronically hypoxic rats and in the ovine fetal lung. However, the role of Rho kinase in mediating pulmonary vasoconstriction after NO synthesis inhibition has not been examined in the intact rat. To address this question, cardiovascular responses to the Rho kinase inhibitor fasudil were studied at baseline and after administration of an NO synthesis inhibitor. In the intact rat, intravenous injections of fasudil cause dose-dependent decreases in systemic arterial pressure, small decreases in pulmonary arterial pressure, and increases in cardiac output. l-NAME caused a significant increase in pulmonary and systemic arterial pressures and a decrease in cardiac output. The intravenous injections of fasudil after l-NAME caused dose-dependent decreases in pulmonary and systemic arterial pressure and increases in cardiac output, and the percent decreases in pulmonary arterial pressure in response to the lower doses of fasudil were greater than decreases in systemic arterial pressure. The Ca++ entry blocker isradipine also decreased pulmonary and systemic arterial pressure in l-NAME-treated rats. Infusion of sodium nitroprusside restored pulmonary arterial pressure to baseline values after administration of l-NAME. These data provide evidence in support of the hypothesis that increases in pulmonary and systemic vascular resistance following l-NAME treatment are mediated by Rho kinase and Ca++ entry through L-type channels, and that responses to l-NAME can be reversed by an NO donor.

Nitric oxide inhalation: effects on the ovine neonatal pulmonary and systemic circulations

1996 ◽  
Vol 8 (3) ◽  
pp. 431 ◽  
Author(s):  
V DeMarco ◽  
JW Skimming ◽  
TM Ellis ◽  
S Cassin
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Hypertension ◽  
Arterial Pressure ◽  
Pulmonary Circulation ◽  
Pulmonary Arterial Pressure ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Minimum Concentration ◽  
Pulmonary Vasoconstriction ◽  
Pulmonary Arterial ◽  
Inhaled No

Others have shown that inhaled nitric oxide causes reversal of pulmonary hypertension in anaesthetized perinatal sheep. The present study examined haemodynamic responses to inhaled NO in the normal and constricted pulmonary circulation of unanaesthetized newborn lambs. Three experiments were conducted on each of 7 lambs. First, to determine a minimum concentration of NO which could reverse acute pulmonary hypertension caused by infusion of the thromboxame mimic U46619, the haemodynamic effects of 5 different doses of inhaled NO were examined. Second, the effects of inhaling 80 ppm NO during hypoxic pulmonary vasoconstriction were examined. Finally, to determine if tachyphalaxis occurs during NO inhalation, lambs were exposed to 80 ppm NO for 3 h during which time pulmonary arterial pressure was doubled by infusion of U46619. Breathing NO (80 ppm) caused a slight but significant decrease in pulmonary vascular resistance (PVR) in lambs with normal pulmonary arterial pressure (PAP). Nitric oxide, inhaled at concentrations between 10 and 80 ppm for 6 min (F1O2 = 0.60), caused decreases in PVR when PAP was elevated with U46619. Nitric oxide acted selectively on the pulmonary circulation, i.e. no changes occurred in systemic arterial pressure or any other measured variable. Breathing 80 ppm NO for 6 min reversed hypoxic pulmonary vasoconstriction. In the chronic exposure study, inhaling 80 ppm NO for 3 h completely reversed U46619-induced pulmonary hypertension. Although arterial methaemoglobin increased during the 3-h exposure to 80 ppm NO, there was no indication that this concentration of NO impairs oxygen loading. These data demonstrate that NO, at concentrations as low as 10 ppm, is a potent, rapid-action, and selective pulmonary vasodilator in unanaesthetized newborn lambs with elevated pulmonary tone. Furthermore, these data support the use of inhaled NO for treatment of infants with pulmonary hypertension.

Inhalation of the ETAreceptor antagonist LU-135252 selectively attenuates hypoxic pulmonary vasoconstriction

2008 ◽  
Vol 294 (2) ◽  
pp. R601-R605 ◽  
Author(s):  
Bodil Petersen ◽  
Maria Deja ◽  
Roland Bartholdy ◽  
Bernd Donaubauer ◽  
Sven Laudi ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Receptor Antagonist ◽  
Experimental Model ◽  
Pulmonary Arterial Pressure ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Pulmonary Vasculature ◽  
Mean Pulmonary Arterial Pressure ◽  
Pulmonary Vasoconstriction ◽  
Pulmonary Arterial ◽  
To Receive

Endogenous endothelin (ET)-1 modulates hypoxic pulmonary vasoconstriction (HPV). Accordingly, intravenously applied ETAreceptor antagonists reduce HPV, but this is accompanied by systemic vasodilation. We hypothesized that inhalation of an ETAreceptor antagonist might act selectively on the pulmonary vasculature and investigated the effects of aerosolized LU-135252 in an experimental model of HPV. Sixteen piglets (weight: 25 ± 1 kg) were anesthetized and mechanically ventilated at an inspiratory oxygen fraction (FiO2) of 0.3. After 1 h of hypoxia at FiO20.15, animals were randomly assigned either to receive aerosolized LU-135252 as bolus (0.3 mg/kg for 20 min; n = 8, LU group), or to receive aerosolized saline ( n = 8, controls). In all animals, hypoxia significantly increased mean pulmonary arterial pressure (32 ± 1 vs. 23 ± 1 mmHg; P < 0.01; means ± SE) and increased arterial plasma ET-1 (0.52 ± 0.04 vs. 0.37 ± 0.05 fmol/ml; P < 0.01) compared with mild hyperoxia at FiO20.3. Inhalation of LU-135252 induced a significant and sustained decrease in mean pulmonary arterial pressure compared with controls (LU group: 27 ± 1 mmHg; controls: 32 ± 1 mmHg; values at 4 h of hypoxia; P < 0.01). In parallel, mean systemic arterial pressure and cardiac output remained stable and were not significantly different from control values. Consequently, in our experimental model of HPV, the inhaled ETAreceptor antagonist LU-135252 induced selective pulmonary vasodilation without adverse systemic hemodynamic effects.

Role of leukotriene C4 in pulmonary hypertension: platelet-activating factor vs. hypoxia

1990 ◽  
Vol 68 (4) ◽  
pp. 1628-1633 ◽  
Author(s):  
D. Davidson ◽  
M. Singh ◽  
G. F. Wallace
Keyword(s):  
Pulmonary Hypertension ◽  
Arterial Pressure ◽  
Pulmonary Arterial Pressure ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Platelet Activating Factor ◽  
Lung Parenchyma ◽  
Base Line ◽  
Leukotriene C4 ◽  
Pulmonary Vasoconstriction ◽  
Pulmonary Arterial

The aim of this study was to determine whether leukotriene C4 (LTC4) is a mediator of hypoxic pulmonary vasoconstriction. We hypothesized that similar increases in LTC4, detected in the lung parenchyma and pulmonary vascular compartment during cyclooxygenase blockade with indomethacin (INDO), would be observed during an equal increase in pulmonary arterial pressure caused by acute alveolar hypoxia (HYP, 100% N2) or platelet-activating factor (PAF, 10 micrograms into the pulmonary artery). Rat lungs were perfused at constant flow in vitro with an albumin-Krebs-Henseleit solution. Mean pulmonary arterial pressure (n = 6 per group) increased from a base line of 10.9 +/- 1.2 to 15.8 +/- 2.1 (HYP + INDO) and 15.5 +/- 1.9 (SE) Torr (PAF + INDO). LTC4 levels increased only in response to PAF + INDO; perfusate levels increased from 0.4 +/- 0.07 to 5.3 +/- 1.1 ng/40 ml, and lung parenchymal levels increased from 1.9 +/- 0.07 to 22.8 +/- 5.3 ng/lung. Diethylcarbamazine (lipoxygenase inhibitor) reduced PAF-induced lung parenchymal levels of LTC4 by 68% and pulmonary hypertension by 63%. We conclude that 1) LTC4 is not a mediator of hypoxic pulmonary vasoconstriction and 2) intravascular PAF is a potent stimulus for LTC4 production in the lung parenchyma.

Effects of Hemoglobin on Pulmonary Arterial Pressure and Pulmonary Vascular Resistance in Patients with Chronic Emphysema

Respiration ◽  
2000 ◽  
Vol 67 (5) ◽  
pp. 502-506 ◽  
Author(s):  
Akira Nakamura ◽  
Norio Kasamatsu ◽  
Ikko Hashizume ◽  
Takushi Shirai ◽  
Suguru Hanzawa ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Pulmonary Vascular Resistance ◽  
Vascular Resistance ◽  
Pulmonary Arterial Pressure ◽  
Pulmonary Arterial

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.

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