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Advances in Internal Medicine 1967
Review
Topics: Altitude; Humans; Hypoxia; Pulmonary Circulation; Pulmonary Edema
PubMed: 5334718
DOI: No ID Found -
Biomedical and Environmental Sciences :... Feb 2013To study the effect of Simulated Microgravity and its Associated Mechanism on Pulmonary Circulation in Rats).
OBJECTIVE
To study the effect of Simulated Microgravity and its Associated Mechanism on Pulmonary Circulation in Rats).
METHODS
Rat tail-suspension model was used to simulate the physiological effects of microgravity and changes in pulmonary blood vessel morphology, pulmonary arterial and venous blood pressure, pulmonary vascular resistance, pulmonary vasomotoricity, as well as the regulation of pulmonary circulation by cytokines produced and released by the lung of rats were measured.
RESULTS
The walls of pulmonary blood vessels of rats were thickened, and the pulmonary artery was reconstructed with increased pulmonary vascular resistance. The pulmonary blood vessels of rats became more prone to dilation as contractions increased. Rat epithelial Adrenomedulin gene transcription and protein expression were upregulated. The level of basic fibroblast growth Factor of rat was also elevated.
CONCLUSION
Findings from the present study on rats revealed that the microgravity can affect pulmonary blood vessel structure, pulmonary arterial pressure, and pulmonary blood vessel self-regulation and cytokine production.
Topics: Animals; Hemodynamics; Male; Pulmonary Artery; Pulmonary Circulation; Rats; Rats, Wistar; Weightlessness
PubMed: 23336135
DOI: 10.3967/0895-3988.2013.02.006 -
Physiological Research 1991Oxygen tension is known to control the pulmonary vascular tone. We reviewed three hypotheses that try to explain the mechanism whereby hypoxia is sensed in the lung... (Review)
Review
Oxygen tension is known to control the pulmonary vascular tone. We reviewed three hypotheses that try to explain the mechanism whereby hypoxia is sensed in the lung tissue. The first hypothesis concerns the role of the oxygen binding hemoprotein cytochrome P-450. Studies using various inhibitors and activators of cytochrome P-450 show that this enzyme affects pulmonary vascular tone. The data are, however, contradictory. The second hypothesis postulates that hypoxia reduces the synthesis of vasodilator oxygen radicals in the lung. This hypothesis is quite well supported by experimental data. The third hypothesis, similarly widely documented, states that slowing of the respiratory chain and altered cellular energetics is crucial for sensing of hypoxia. In this case, however, it is not exactly clear how changes in cellular energetics are connected with vascular tone. The possibility exists that changes in both the cytochrome P-450 activity and in the rate of electrons flow in the respiratory chain may alter the amount of oxygen radicals in the cells and, similarly as in the "oxygen radicals" hypothesis, govern calcium channels through the control of the redox status of these channels.
Topics: Oxidation-Reduction; Oxygen; Pulmonary Circulation
PubMed: 1812974
DOI: No ID Found -
Circulation Feb 1966
Topics: Altitude; Arterioles; Humans; Pulmonary Circulation; Pulmonary Edema
PubMed: 25823089
DOI: 10.1161/01.cir.33.2.177 -
Research in Veterinary Science Oct 2013It has been observed that microbubbles may pass through the pulmonary circulation of dogs and humans during exercise. In humans, this phenomenon has been associated with...
It has been observed that microbubbles may pass through the pulmonary circulation of dogs and humans during exercise. In humans, this phenomenon has been associated with lower pulmonary artery pressures, enhanced right ventricular function and greater exercise capacity. In the exercising Thoroughbred horse, extraordinarily high cardiac outputs exert significant pulmonary vascular stresses. The aim of this study was to determine, using contrast echocardiography, whether Thoroughbred horses performing strenuous exercise developed pulmonary transit of agitated contrast microbubbles (PTAC). At rest, agitated contrast was observed in the right ventricle, but not in the left ventricle. However, post-exercise microbubbles were observed in the left ventricle, confirming the occurrence of PTAC with exercise but not at rest. Further investigation is warranted to investigate whether this phenomenon may be associated with superior physiology and performance measures as has been implicated in other species.
Topics: Animals; Contrast Media; Horses; Lung; Male; Microbubbles; Physical Conditioning, Animal; Pulmonary Circulation
PubMed: 23642486
DOI: 10.1016/j.rvsc.2013.04.002 -
American Journal of Physiology.... Aug 2001High levels of circulating catecholamines are found in the fetus, and fetal stress and birth induce a marked surge in catecholamine secretion. Little is known about the...
High levels of circulating catecholamines are found in the fetus, and fetal stress and birth induce a marked surge in catecholamine secretion. Little is known about the role of catecholamines on the fetal pulmonary circulation. To determine the effects of catecholamines on the pulmonary vascular tone, we tested the hemodynamic response to norepinephrine and dopamine infusion in chronically prepared late-gestation fetal lambs. We found that norepinephrine infusion (0.5 microg. kg(-1). min(-1)) increased pulmonary artery pressure (PAP) by 10 +/- 1% (P < 0.01), left pulmonary artery blood flow by 73 +/- 14% (P < 0.01), and decreased pulmonary vascular resistance (PVR) by 33 +/- 6% (P < 0.01). The pulmonary vasodilator effect of norepinephrine was abolished after nitric oxide synthase inhibition. Dopamine infusion at 5 microg. kg(-1). min(-1) did not significantly change PVR. Conversely, dopamine infusion at 10 microg. kg(-1). min(-1) increased PAP (P < 0.01) and progressively increased PVR by 30 +/- 14% (P < 0.01). These results indicate that catecholamines may modulate basal pulmonary vascular tone in the ovine fetus. We speculate that catecholamines may play a significant role in the maintenance of the fetal pulmonary circulation and in mediating changes in the transitional pulmonary circulation.
Topics: Adrenergic alpha-Agonists; Animals; Blood Pressure; Dopamine; Enzyme Inhibitors; Female; Fetus; Nitroarginine; Norepinephrine; Pregnancy; Pulmonary Circulation; Sheep; Vascular Resistance
PubMed: 11448866
DOI: 10.1152/ajpregu.2001.281.2.R607 -
The European Respiratory Journal Nov 2019
Comparative Study
Topics: Bias; Cardiac Catheterization; Diagnostic Errors; Echocardiography, Stress; Female; Humans; Male; Pulmonary Circulation
PubMed: 31558657
DOI: 10.1183/13993003.00881-2019 -
Nihon Ishikai Zasshi. Journal of the... Feb 1966
Topics: Humans; In Vitro Techniques; Lung Diseases; Pulmonary Circulation
PubMed: 5949719
DOI: No ID Found -
Polskie Archiwum Medycyny Wewnetrznej 1965
Topics: Humans; Pulmonary Circulation
PubMed: 5831388
DOI: No ID Found -
Journal of Pediatric Surgery Mar 2013Tracheal occlusion (TO) promotes fetal lung growth through an increase in intraluminal pressure. Although evidence suggests that fetal TO (FETO) decreases the occurrence...
BACKGROUND
Tracheal occlusion (TO) promotes fetal lung growth through an increase in intraluminal pressure. Although evidence suggests that fetal TO (FETO) decreases the occurrence of pulmonary hypertension in severe congenital diaphragmatic hernia, controversies on its effect on the pulmonary circulation remain. Therefore, we investigated the effects of FETO on the lung hemodynamics in a chronically catheterized fetal lamb model.
METHODS
Fifteen pregnant ewes were operated on between 125 and 128 days of gestation (term: 145 days). Catheters and ultrasonic flow transducer were placed through a left thoracotomy in the lamb fetus to determine aortic, pulmonary and left atrial pressures, and left pulmonary artery blood flow. A balloon was positioned between the carina and vocal cords under fetoscopic control. The animals were assigned to either control (n=6) or FETO (n=9) groups. TO was performed by inflating the balloon. We studied the acute effects of temporary (2-h) and prolonged (4-day) TO on basal pulmonary vascular tone and on the pulmonary vascular reactivity to acetylcholine and to increased fetal oxygen tension.
RESULTS
We found that left pulmonary blood flow (LPA) increased and pulmonary vascular resistance (PVR) decreased by 20% during brief TO (p<0.05). After balloon deflation, LPA blood flow further increased by 40%, and PVR decreased by 50% compared to baseline values (p<0.05). In contrast, no change in LPA blood flow or PVR was observed during prolonged TO. Moreover, the vasodilator responses to acetylcholine and to increased fetal PaO2 were blunted during TO.
CONCLUSIONS
These data indicate that antenatal tracheal occlusion promotes active pulmonary vasodilation, which is partly blunted by the mechanical effects of elevation of the intraluminal pressure.
Topics: Animals; Lung; Muscle, Smooth, Vascular; Pressure; Pulmonary Circulation; Sheep; Trachea
PubMed: 23480900
DOI: 10.1016/j.jpedsurg.2012.08.024