In situ expression of ICAM-1 and its mRNA in the lung tissue of asthmatic rats

In situ expression of ICAM-1 and ICAM-1 mRNA on the lung tissue of asthmatic rats was studied by immunohistochemical staining and in situ hybridization, respectively. The results showed that in normal rats ICAM-1 expression was rare on the endothelium of pulmonary artery and vein, and on the bronchial and alveolar epithelium. The distribution of ICAM-1 expression on the different part of lung tissue of asthmatic rats was similar to that of normal rats, but the level of ICAM-1 expression was significantly increased on the endothelium of pulmonary artery (EPA) and vein (EPV), bronchial epithelium (BEP) and alveolar epithelium (AEP) compared with those of normal and sensitized controls. The distribution and expression of ICAM-1 mRNA on the different part of lung tissue of normal and asthmatic rats were similar to that of ICAM-1 expression. In asthmatic rats, the expression of ICAM-1 mRNA on AEP and EPV was increased significantly compared with those of normal and sensitized controls. It is concluded that the increase of ICAM-1 expression on endothelium of pulmonary vessels, epithelium of broncheoli and alveoli may play an important role of inflammatory cell infiltration in asthmatic rats, and the increased expression of ICAM-1 in asthmatic rats was caused by the increase of expression of ICAM-1 mRNA.

[A model of isobaric hypoxic pulmonary hypertension in rats]

Male Wistar rats were kept in isobaric hypoxic chamber (O2 = 10%) with intermittent hypoxia for 1, 2, 4 weeks (6 hrs/day, 6 days/wk). The pulmonary arterial blood pressures increased significantly after 1 week of hypoxia, reached the maximum at 2 weeks of hypoxia and thereafter plateaued in 4 weeks of hypoxia. The elevated Pap were paralleled by increase in the right ventricular blood pressure. The prolonged exposure to hypoxia also led to the right ventricular hypertrophy, which were presented in the increase in both the weight ratio of right ventricle to the left ventricle plus septum and to the body weight. There were no significant hemodynamic changes in the pulmonary circulation by the 24 hours hypoxia. The result suggested that the intermittent hypoxia can lead to the pulmonary hypertension in the model.

Selective distribution of beta- and alpha 1-adrenoceptors in rat lung visualized by autoradiography

The distribution of beta- and alpha 1-adrenoceptors was studied in rat lung by autoradiography using two ligands: 125-Iodocyanopindolol for beta-adrenoceptors, and 125-Iodo-BE 2254 for alpha 1-adrenoceptors. Beta-adrenoceptors were widely distributed in the lung parenchyma and on the walls of the airways (bronchioles). The epithelium of the bronchioles showed a higher density of beta-adrenoceptors than the smooth muscle. The blood vessels (veins) seemed to have very few beta-adrenoceptors. Alpha 1-adrenoceptors were found in approximately ten fold smaller amounts than beta-adrenoceptors in the lung parenchyma and on the small veins. On the bronchioles, an extremely small number of alpha 1-adrenoceptors was visible.

Assessment by radionuclide angiography of right and left ventricular function in chronic bronchitis and emphysema

Non-invasive measurements of right and left ventricular ejection fraction (RVEF, LVEF) by multiple-gated equilibrium radionuclide ventriculography were performed in 18 control subjects, 16 patients with angina pectoris, and 45 patients with hypoxic chronic bronchitis and emphysema. The mean RVEF in the control subjects was 0.62 +/- 0.09 (SD), which was not significantly different from the mean RVEF in the patients with angina (0.60 +/- 0.09), but was significantly higher (p less than 0.01) than the mean value in patients with chronic bronchitis and emphysema (0.45 +/- 0.11). LVEF was not significantly different in the groups studied. There was a significant correlation between LVEF and RVEF only in patients with chronic bronchitis and emphysema (p less than 0.001). Those patients with chronic bronchitis and emphysema who had clinical evidence of cor pulmonale at the time of the study had significantly lower values of RVEF and LVEF (p less than 0.001) than patients with no previous cor pulmonale or those who had had cor pulmonale in the past. There was a significant correlation between RVEF and arterial oxygen (p less than 0.01) and carbon dioxide tensions (p less than 0.05). Reduced RVEF in patients with chronic bronchitis and emphysema may be an early indicator of the development of cor pulmonale and may be useful as a non-invasive method of assessing the effects of therapeutic interventions.

Can right ventricular performance be assessed by equilibrium radionuclide ventriculography?

Although right ventricular function may be examined by following the passage (first pass) of a bolus of radionuclide through the right heart before it reaches the left heart, the counts detected with conventional gamma cameras in such a short time interval are low; moreover, repeated determinations would result in an unacceptable radiation burden to the patient. We have modified the gated equilibrium blood pool method to allow repeated assessment of the right ventricular ejection fraction (RVEF) and have compared the results with the first-pass method in 43 patients. Good agreement was obtained between the two methods (r = 0.91, p less than 0.001). The mean difference between the two methods was 0.04 with an intra-observer variation for the equilibrium studies of 0.03 and an inter-observer difference of 0.04. The mean difference in RVEF for seven patients studied on two separate occasions 30 minutes apart was only 0.02. In four patients the mean RVEF measured at rest was 0.44 +/- 0.05 (SEM) and after exercise it was 0.48 +/- 0.06. After infusion of isoprenaline at 1 microgram/min the mean rose to 0.64 +/- 0.04 (p less than 0.02) and after infusion of a new beta 1-sympathomimetic agent, prenalterol, at doses of 1 and 2 mg it was 0.56 +/- 0.02 (p less than 0.02) and 0.59 +/- 0.03 (p less than 0.01) respectively, where the significance levels are relative to the resting values. In nine patients with good ventricular function the vasodilator nifedipine caused right and left ventricular ejection fractions to increase by the same amount; while in six patients with severe impairment of left ventricular function due to ischaemic heart disease the RVEF increased from 0.58 +/- 0.03 to 0.73 +/- 0.03 (p less than 0.01) after 2 mg of prenalterol, but the left ventricular ejection fraction increased only from 0.22 +/- 0.04 to 0.26 +/- 0.04. We conclude that repeated estimation of right ventricular performance is possible by equilibrium radionuclide ventriculography.