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Annual Review of Physiology 1966
Review
Topics: Animals; Humans; Pulmonary Circulation; Respiration
PubMed: 5322974
DOI: 10.1146/annurev.ph.28.030166.001141 -
Arzneimittel-Forschung May 1975
Topics: Aminorex; Animals; Blood Pressure; Dogs; Oxazoles; Pulmonary Circulation; Stimulation, Chemical
PubMed: 1242336
DOI: No ID Found -
Journal of Applied Physiology... Apr 2011Recent experimental and imaging studies suggest that the influence of gravity on the measured distribution of blood flow in the lung is largely through deformation of...
Recent experimental and imaging studies suggest that the influence of gravity on the measured distribution of blood flow in the lung is largely through deformation of the parenchymal tissue. To study the contribution of hydrostatic effects to regional perfusion in the presence of tissue deformation, we have developed an anatomically structured computational model of the pulmonary circulation (arteries, capillaries, veins), coupled to a continuum model of tissue deformation, and including scale-appropriate fluid dynamics for blood flow in each vessel type. The model demonstrates that both structural and the multiple effects of gravity on the pulmonary circulation make a distinct contribution to the distribution of blood. It shows that postural differences in perfusion gradients can be explained by the combined effect of tissue deformation and extra-acinar blood vessel resistance to flow in the dependent tissue. However, gravitational perfusion gradients persist when the effect of tissue deformation is eliminated, highlighting the importance of the hydrostatic effects of gravity on blood distribution in the pulmonary circulation. Coupling of large- and small-scale models reveals variation in microcirculatory driving pressures within isogravitational planes due to extra-acinar vessel resistance. Variation in driving pressures is due to heterogeneous large-vessel resistance as a consequence of geometric asymmetry in the vascular trees and is amplified by the complex balance of pressures, distension, and flow at the microcirculatory level.
Topics: Hemodynamics; Humans; Lung; Models, Cardiovascular; Pulmonary Circulation; Regional Blood Flow
PubMed: 21292845
DOI: 10.1152/japplphysiol.00775.2010 -
The European Respiratory Journal.... Dec 1990The bronchial circulation, like the pulmonary circulation, is subjected to the mechanical effects of lung inflation with each breath. Lung inflation, in all species... (Review)
Review
The bronchial circulation, like the pulmonary circulation, is subjected to the mechanical effects of lung inflation with each breath. Lung inflation, in all species studied, decreases the bronchial blood flow. This is due to changes in both lung volume and transpulmonary pressure. With this reduction of flow there is also a relative increase in the proportion of bronchial blood flow drained from the lung through systemic veins. These changes are probably due to purely mechanical effects on the systemic-to-pulmonary anastomotic bronchial blood vessels with both compression and stretching of the vessels.
Topics: Animals; Bronchi; Dogs; Lung; Pulmonary Circulation; Sheep; Vascular Resistance
PubMed: 2076152
DOI: No ID Found -
Modern Concepts of Cardiovascular... Nov 1967
Topics: Altitude; Child; Child, Preschool; Heart Defects, Congenital; Humans; Hypertension, Pulmonary; Infant; Infant, Newborn; Infant, Newborn, Diseases; Pulmonary Circulation; Tolazoline
PubMed: 5621078
DOI: No ID Found -
Anesthesia and Analgesia Aug 2007Perioperative management of neonates after the Norwood procedure is extremely complex. Limited reserve of the neonatal single ventricle and the parallel arrangement of... (Review)
Review
Perioperative management of neonates after the Norwood procedure is extremely complex. Limited reserve of the neonatal single ventricle and the parallel arrangement of the pulmonary and systemic circuits result in a tenuous balance between pulmonary and systemic blood flows. Precise manipulations of both pulmonary and systemic vascular resistance are necessary to prevent excessive pulmonary blood flow at the expense of systemic oxygen delivery. An emerging treatment strategy aimed at improving early mortality is the intraoperative administration of phenoxybenzamine, a profound systemic vasodilator. Maximum systemic vasodilation is thought to reduce afterload of the single ventricle and produce a more stable parallel circulation by ameliorating the postoperative fluctuations in systemic vascular resistance. Although this strategy has gained popularity at many centers, it is not without scrutiny. The following review provides an overview of the pharmacology of phenoxybenzamine, the surgical and physiologic implications of the Norwood procedure, and a discussion of the pros and cons of phenoxybenzamine administration.
Topics: Cardiopulmonary Bypass; Humans; Hypoplastic Left Heart Syndrome; Infant, Newborn; Monitoring, Intraoperative; Phenoxybenzamine; Pulmonary Circulation
PubMed: 17646482
DOI: 10.1213/01.ane.0000275185.44796.92 -
Trends in Cardiovascular Medicine Nov 2003Determining how the pulmonary vascular system is formed, maintained, or disrupted during development and disease represents a major challenge in contemporary lung... (Review)
Review
Determining how the pulmonary vascular system is formed, maintained, or disrupted during development and disease represents a major challenge in contemporary lung biology. Whereas it is appreciated that cellular proliferation, differentiation, migration, and apoptosis need to be carefully controlled in order to attain pulmonary vascular homeostasis, knowledge of the underlying cellular and molecular mechanisms involved remains surprisingly limited. Because homeobox genes represent master regulators of organogenesis and tissue patterning, it is likely that these transcription factors play a critical role in the formation of blood vessels within the lung, as well as in pathologic states in which the highly ordered structure of the pulmonary vascular tree is compromised. The aim of this review is to discuss some of the known functions of homeobox genes in the vasculature, and to extrapolate these findings to their potential roles in developing and diseased pulmonary vessels.
Topics: Animals; Genes, Homeobox; Homeostasis; Humans; Lung; Pulmonary Circulation; Sheep; Vascular Diseases
PubMed: 14596950
DOI: 10.1016/j.tcm.2003.09.001 -
Journal of Applied Physiology... Apr 1991We previously reported that Fischer (F) rat lungs developed more extensive injury when challenged with oxidants than age-matched Sprague-Dawley (SD) rat lungs. We now... (Comparative Study)
Comparative Study
We previously reported that Fischer (F) rat lungs developed more extensive injury when challenged with oxidants than age-matched Sprague-Dawley (SD) rat lungs. We now describe a reduced pulmonary vascular response to alveolar hypoxia and angiotensin II (ANG II) in F compared with SD rats. The comparative studies were performed with isolated lungs perfused with salt solution or blood, catheter-implanted awake rats, and isolated main pulmonary arterial rings. Isolated lungs from F rats perfused with either blood or salt solution had reduced vasoconstriction in comparison with lungs from SD rats when exposed to alveolar hypoxia or challenged with ANG II. Instrumented awake F rats had a smaller mean increase in total pulmonary vascular resistance (PVR) than SD rats (35 vs. 94 mmHg.min.l-1, P less than 0.05) when challenged with 8% oxygen. The contractile response of isolated pulmonary artery but not thoracic aortic rings to KCl and ANG II was reduced in F compared with SD rats. In addition, F rats exposed to 4 wk of hypobaric hypoxia developed less pulmonary hypertension and right ventricular hypertrophy (when corrected for the hematocrit) than SD rats. We conclude that the oxidant stress-sensitive inbred F rat strain is characterized by a lung vascular bed that is relatively unresponsive to vasoconstricting stimuli. The mechanism underlying this genetic difference in lung vascular control remains to be defined.
Topics: Altitude; Angiotensin II; Animals; Hypoxia; In Vitro Techniques; Male; Perfusion; Pulmonary Circulation; Rats; Rats, Inbred F344; Rats, Inbred Strains; Species Specificity; Vasoconstriction
PubMed: 2055865
DOI: 10.1152/jappl.1991.70.4.1861 -
Journal of Applied Physiology... Mar 1991The pulmonary circulation in the adult is characterized by being relatively distensible, but whether the newborn lung shares this feature is less certain. We perfused...
The pulmonary circulation in the adult is characterized by being relatively distensible, but whether the newborn lung shares this feature is less certain. We perfused isolated lungs treated with indomethacin from lambs of four ages (less than 1, 2-4, 12-14, and 30-32 days) to determine the effects of increasing left atrial pressure on the pulmonary vascular pressures measured by vascular inflow and outflow occlusion. An index of pulmonary vascular distensibility was assessed by comparing the slope of the pulmonary vascular pressure at the upstream end of a region as a function of the pressure at the downstream end of the region. A vascular distensibility index (VDI) of 1 indicates a rigid nondistensible system, whereas a VDI less than 1 indicates some degree of distensibility. During normoxia, lungs from all age groups were relatively indistensible as determined by VDI for the total vasculature (VDItotal) as well as for the different regions based on occlusion pressures (VDIarterial, VDImiddle, and VDIvenous). There were significant effects of age on the VDItotal, with decreases in the normoxic values occurring over the first 12-14 days of age, indicating an increase in pulmonary vascular distensibility. Only the VDIvenous was similarly affected by increasing neonatal age. Hypoxia significantly reduced the VDItotal in these same age groups. In addition, hypoxia, which increased the pressure gradients of the arterial and middle regions, significantly increased the VDIarterial in the youngest and oldest age groups but significantly decreased the VDImiddle at all ages by approximately 50%. In summary, we observed age-related changes in the vascular distensibility of the pulmonary circulation, with the VDItotal decreasing with increasing postnatal age.(ABSTRACT TRUNCATED AT 250 WORDS)
Topics: Animals; Animals, Newborn; Blood Pressure; Hypoxia; In Vitro Techniques; Indomethacin; Perfusion; Pulmonary Artery; Pulmonary Circulation; Pulmonary Veins; Sheep; Vascular Resistance; Vasoconstriction
PubMed: 2032998
DOI: 10.1152/jappl.1991.70.3.1315 -
Respiration Physiology Mar 1998We investigated how signals arising from peripheral chemoreceptors could affect pulmonary vasculature in rats. Effects of the hypoxic exposure (10%) on mean pulmonary...
We investigated how signals arising from peripheral chemoreceptors could affect pulmonary vasculature in rats. Effects of the hypoxic exposure (10%) on mean pulmonary arterial pressure (mPAP), abdominal aortic flow (Q) and the estimated total pulmonary vascular resistance (mPAP/Q) were determined in anesthetized, artificially ventilated, carotid sinus nerve intact or chemodenervated rats. The pressor response of PAP to hypoxia seen in intact rats changed to the depressor response after chemodenervation. Hypoxia elicited a decrease in Q and an increase in mPAP/Q in both intact and chemodenervated rats. Selective carotid body stimulation by the intra-carotid injection of sodium cyanide (NaCN) in normoxia elicited an immediate but transient increase in PAP and Q before and after bilateral vagotomy. The peak change in PAP slightly preceded that in Q. These responses to NaCN were completely abolished by chemodenervation. These results indicate that the immediate chemoreflex contributes to the short-term regulation of pulmonary vasculature in rats.
Topics: Animals; Blood Pressure; Carotid Body; Chemoreceptor Cells; Denervation; Hypoxia; Pulmonary Circulation; Rats; Recurrence; Sodium Cyanide; Stimulation, Chemical; Vascular Resistance
PubMed: 9628233
DOI: 10.1016/s0034-5687(97)00126-6