1,721,120 research outputs found
Interleukin-6 and lung inflammation: evidences of a causing role in indicing respiratory system resistance increments.
No full textEffect of perfusate temperature on pulmonary vascular resistance and compliance by arterial and venous occlusion in the rat.
No full textAbstract The effect of different temperatures of perfusing
fluid was tested on the pulmonary circulation of the rat.
With increasing temperature, a decrease in overall pulmonary
vascular resistance was observed, which
depended on the associated reductions of arterial, venous
and capillary vascular resistances. The highest
sensitivity to temperature changes was exhibited by the
venous segment. The overall sensitivity of pulmonary
vessels to temperature caused a reduction in hydraulic
resistance of about 1% for each 1 C temperature
increment. Compliance of pulmonary vessels increased
when perfusate temperature was increased from between
25 and 35 C to 45 C, probably due to a direct effect of
temperature on the stiffness of the vessel walls
Produzione di calore dei muscoli cardiaco e respiratori a riposo e durante esercizio muscolare
No full text
Osservazioni sugli effetti di cambiamenti di PaCO2 sulla differenza artero-venosa di ossigeno per la circolazione cerebrale nell'uomo
No full textIL-6 increases airway resistance in the rat
No full textThe end-inspiratory occlusion method was applied in anesthetized, paralyzed, positive pressureventilated
rats to assess the possible effects of interleukin IL-6 on respiratory mechanics in normal rats.
Measurements were made in control rats and in experimental animals before and after IL-6 intraperitoneal
administration (15 ng/100 g), including static respiratory system elastance, the resistance to airflow
and to the movement of respiratory system tissues, and the resistance due to lung stress–relaxation and
mechanical inhomogeneity. Respiratory system hysteresis was also measured, and total mechanical
breathing work rate and its elastic and resistive components calculated.
Control rats did not exhibit alteration in respiratory mechanics during the observation period (30 min),
while the experimental animals showed an increase in resistive pressure dissipations starting 15 min
after IL-6 administration. Dose-dependent effects were also investigated.
In a rather delayed effect, IL-6 increased the resistance to airflow and to the movement of respiratory
system tissues, the resistance due to lung stress–relaxation and mechanical inhomogeneity, and the
related resistive mechanical breathing work rate, and left the elastic pressure dissipation unaltered.
The mechanisms by which IL-6 may contribute to the airways resistance increase which is seen in different
respiratory diseases are likewise discussed
The effects of prone with respect to supine position on stress-relaxation, respiratory mechanics and the work of breathing measured by the end-inflation method in the rat.
No full textPurpose: The working hypothesis is that the prone position with respect to supine may change the geometric configuration of the lungs inside the chest wall, thus their reciprocal mechanical interactions, leading to possible effects on stress relaxation phenomena and respiratory mechanics. Method: The effects of changing body posture from supine to prone on respiratory system mechanics, particularly on stress relaxation, were investigated in the rat by the end-inflation occlusion method. Results: In the prone with respect to supine position, an increment of the frictional resistance of the airway (from 0.13 ± 0.01 to 0.19 ± 0.02 cm H2O/l sec−1, p < 0.05) and a decrement of the stress relaxation-linked pressure dissipation (from 0.51 ± 0.05 to 0.45 ± 0.05 cm H2O/l sec−1, p < 0.01) were found. Respiratory system elastance and total resistive pressure dissipation did not change significantly. Accordingly, a significant increase of the frictional “ohmic” mechanical inspiratory work of breat..
The effect of N-Nitro-L-Arginine methyl ester, a nitric oxide sybthase inhibitor, on respiratory mechanics in rats.
No full text<i>Background:</i> Data describing the inhibitory effects of nitric oxide synthase (NOS) on respiratory mechanics are conflicting, and no data are available concerning possible effects on the viscoelasticity of the respiratory system, on the inspiratory work of breathing (WOB) or on respiratory system hysteresis. <i>Objectives:</i> The aim of this study was to measure the effects of NOS inhibition by N<sup>G</sup>-nitro-<i>L</i>-arginine methyl ester (<i>L</i>-NAME) on respiratory mechanics in normal anesthetized rats. <i>Methods:</i> Using the end-inflation occlusion method, it was possible to quantify the ohmic and viscoelastic airway resistance and elastance of the respiratory system. Ohmic resistance is the normalized-to-flow pressure dissipation due to viscous forces opposing the airflow in the airways, as predicted by the Poiseuille law. Viscoelastic resistance is the normalized-to-flow pressure dissipation due to the resistance of respiratory system tissue to deformation during inflation, which is recovered after the arrest of the inspiratory flow (stress relaxation). The inspiratory WOB, its elastic and resistive components, and hysteresis were also calculated. <i>Results:</i><i>L</i>-NAME induced an increment in the ohmic airway resistance and in the resistive ohmic inspiratory WOB. The viscoelastic resistance due to stress relaxation and the elastic properties of the respiratory system were not modified, and no effect was detected on the related components of the inspiratory WOB and on hysteresis. <i>Conclusions:</i> NO acts in normal rats to reduce the ohmic component of airway resistance, decreasing the ohmic inspiratory WOB. The elastic and viscoelastic components are unaltered. Hysteresis is also unaltered, suggesting that NO has negligible effects on alveolar surfactant activity.</jats:p
- …
