Impact of elevated pulmonary blood flow and capillary pressure on lung responsiveness.
نویسندگان
چکیده
Since alterations in pulmonary hemodynamics may lead to airway hyperreactivity, the consequences of individual changes in pulmonary blood flow (Qp) and capillary pressure (Pc) on lung responsiveness were investigated. During maintenance of a steady-state Pc of 5, 10, or 15 mmHg (groups 1-3), acute increases of Qp were generated in isolated, perfused rat lungs by simultaneous pulmonary arterial pressure elevation and venous pressure lowering. Conversely, at constant low (groups 4 and 5) or high Qp (groups 6 and 7), Pc was lowered or elevated by changing, in parallel, the pulmonary arterial and venous pressures. Pulmonary input impedance was measured under baseline conditions and during methacholine provocation (2-18 microg*kg(-1)*min(-1)), whereas the pulmonary hemodynamics were altered in accordance with the group allocation. The airway resistance and constant-phase parenchymal model parameters were identified from the pulmonary input impedance spectra. Increases of Qp at constant Pc had no effect on the basal lung mechanics, whereas they enhanced the lung reactivity to methacholine, particularly when high Pc was maintained [peak airway resistance increases of 299 +/- 99% (SE) vs. 609 +/- 217% at Qp levels of 5 and 10 ml/min, respectively, P < 0.05]. In contrast, the change of Pc at constant Qp slightly deteriorated the basal parenchymal mechanics without affecting the lung responsiveness. These findings suggest that increases in Qp per se may lead to the development of airway hyperreactivity. This phenomenon may contribute to the airway susceptibility under conditions associated with simultaneous elevations in pulmonary vascular pressures and Qp, such as exercise-induced asthma and the situation in children with congenital heart diseases.
منابع مشابه
Steep head-down tilt has persisting effects on the distribution of pulmonary blood flow.
Head-down tilt has been shown to increase lung water content in animals and alter the distribution of ventilation in humans; however, its effects on the distribution of pulmonary blood flow in humans are unknown. We hypothesized that head-down tilt would increase the heterogeneity of pulmonary blood flow in humans, an effect analogous to the changes seen in the distribution of ventilation, by i...
متن کاملRegulation of the pulmonary circulation.
Factors regulating pressure and flow in the lungs are reviewed with particular emphasis on their role in regulating blood flow velocity and distribution within the lung capillaries. The behaviour of the pulmonary arterial, system, alveolar capillaries, and pulmonary venous system are considered individually. The effect of heart disease on lung capillary blood flow is examined.
متن کاملEffect of vitamin C on tracheal responsiveness and pulmonary inflammation in chronic obstructive pulmonary disease model of guinea pig
Introduction: In the present study, the prophylactic effect of vitamin C, as a potent anti-oxidant, on tracheal responsiveness to methacholine and ovalbumin, bronchoalveolar lavage fluid white blood cell (WBC) count and differential count, and also lung pathology in chronic obstructive pulmonary disease (COPD) -guinea pigs (cigarette exposed guinea pigs) were examined. In addition, the relax...
متن کاملPulmonary edema in cardiac surgery.
marizedinthe abstract which you have. I would like to discuss today about the inducing factors of this deliterious complication particularly regarding elevated pulmonary arterial pressure. In an experimental study, the pulmonary arterial pressure was elevated by perfusion technique and the incidence of the pulmonary edema was investigated. The incidence was 14.3% when the pulmonary pressure was...
متن کاملLongitudinal distribution of vascular resistance in the pulmonary arteries, capillaries, and veins.
A new method has been described for measuring the pressure and resistance to blood flow in the pulmonary arteries, capillaries, and veins. Studies were performed in dog isolated lung lobes perfused at constant flow with blood from a donor dog. Pulmonary artery and vein volume and total lobar blood volume were measured by the ether plethysmograph and dyedilution techniques. The longitudinal dist...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Journal of applied physiology
دوره 107 3 شماره
صفحات -
تاریخ انتشار 2009