Effect of blood flow rate and blood flow history on newborn pulmonary microcirculation

Fike, Candice D.; Kaplowitz, Mark R.

doi:10.1152/ajpheart.1991.261.2.h271

Cited by 2 publications

(1 citation statement)

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“…However, under conditions of maximal or submaximal recruitment, increases in blood flow can cause significant increases in microvascular and venous pressures, both in the neonatal (116,148) and adult (57,78) lung. Also, in situations where fractional venous resistance is high (115) or venous distensibility is low (39), increases in blood flow rate will shift the filtration midpoint upstream toward the pulmonary artery (166) resulting in microvascular filtration pressures that approach the pressure in the pulmonary artery. This is shown graphically in the case of neonatal lamb lungs but not in adult rat lungs in Fig.…”

Section: Mechanical Factors That Influence Venous Resistance In Lungsmentioning

confidence: 99%

Role of veins in regulation of pulmonary circulation

Gao¹,

Raj²

2005

American Journal of Physiology-Lung Cellular and Molecular Phys

103

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Pulmonary veins have been seen primarily as conduit vessels; however, over the past two decades, a large amount of evidence has accumulated to indicate that pulmonary veins can exhibit substantial vasoactivity. In this review, the role of veins in regulation of the pulmonary circulation, particularly during the perinatal period and under certain pathophysiological conditions, is discussed. In the fetus, pulmonary veins contribute a significant fraction to total pulmonary vascular resistance. At birth, the veins as well as the arteries relax in response to endothelium-derived nitric oxide and dilator prostaglandins, thereby assisting in the fall in pulmonary vascular resistance. These effects are oxygen dependent and modulated by cGMP-dependent protein kinase. Under chronic hypoxic conditions, pulmonary veins undergo remodeling and demonstrate substantial constriction and hypertrophy. In a number of species, including the human, pulmonary veins are also the primary sites of action of certain vasoconstrictors such as endothelin and thromboxane. In various pathological conditions, there is an increased synthesis of these vasoactive agents that may lead to pulmonary venous constriction, increased microvascular pressures for fluid filtration, and formation of pulmonary edema. In conclusion, the significant role of veins in regulation of the pulmonary circulation needs to be appreciated to better prevent, diagnose, and treat lung disease.

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Section: Mechanical Factors That Influence Venous Resistance In Lungsmentioning

confidence: 99%

Role of veins in regulation of pulmonary circulation

Gao¹,

Raj²

2005

American Journal of Physiology-Lung Cellular and Molecular Phys

103

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Involvement of ryanodine receptors in muscarinic receptor-mediated membrane current oscillation in urinary bladder smooth muscle

Kajioka¹,

Nakayama²,

Asano³

et al. 2005

American Journal of Physiology-Cell Physiology

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The urinary bladder pressure during micturition consists of two components: an initial, phasic component and a subsequent, sustained component. To investigate the excitation mechanisms underlying the sustained pressure, we recorded from membranes of isolated detrusor cells from the pig, which can be used as a model for human micturition. Parasympathomimetic agents promptly evoke a large transient inward current, and subsequently during its continuous presence, oscillating inward currents of relatively small amplitudes are observed. The two types of inward current are considered to cause the phasic and sustained pressure rises, respectively. Ionic substitution and applications of channel blockers revealed that Ca(2+)-activated Cl(-) channels were responsible for the large transient and oscillating inward currents. Furthermore, the inclusion of guanosine 5'-O-(2-thiodiphosphate) in the patch pipette indicates that both inward currents involve G proteins. However, applications of heparin in the patch pipette and of xestospongin C in the bathing solution suggest a signaling pathway other than inositol 1,4,5-trisphosphate (IP(3)) operating in the inward current oscillations, unlike the initial transient inward current. This IP(3)-independent inward current oscillation system required both sustained Ca(2+) influx from the extracellular space and Ca(2+) release from the intracellular stores. These two requirements are presumably SKF-96365-sensitive cation channels and ryanodine receptors, respectively. Experiments with various Ca(2+) concentrations suggested that Ca(2+) influx from the extracellular space plays a major role in pacing the oscillatory rhythm. The fact that distinct mechanisms underlie the two types of inward current may help in development of clinical treatments of, for example, urinary incontinence and residual urine volume control.

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Effect of blood flow rate and blood flow history on newborn pulmonary microcirculation

Cited by 2 publications

References 0 publications

Role of veins in regulation of pulmonary circulation

Role of veins in regulation of pulmonary circulation

Involvement of ryanodine receptors in muscarinic receptor-mediated membrane current oscillation in urinary bladder smooth muscle

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