Chest
Volume 99, Issue 3, March 1991, Pages 637-641
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Lung β-Adrenoceptors in Pulmonary Hypertension*: A Study of Biopsy Specimens in Children with Congenital Heart Disease

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Characteristics of β-adrenoceptors were analyzed using radioligand-binding techniques with 3H-dihydroalprenolol in lung specimens from 11 children with pulmonary hypertension (median age, three years) undergoing surgical repair of congenital heart defects and four pediatric control subjects (median age, five years) undergoing thoracotomy for removal of neoplasms or cysts. Scatchard analysis of 3H-DHA binding to lung membranes showed similar values of the dissociation constant in both groups (Kd = 0.72 ± 0.22 nM in patients vs 1.22 ± 0.22 nM in controls; p = NS). The receptor density was significantly increased in patients in comparison with controls, with respective values of 164 ± 19 and 95 ± 13 fmol/mg of protein (p<0.025), and correlated directly with mean pulmonary arterial pressure (r = 0.82; p<0.0005). No significant relationship was observed between receptor number and pulmonary arterial medial thickness. Thus, the increase in receptor density in these patients may be related to adaptative changes in cells other than vascular smooth muscle. (Chest 1991; 99:637-41)

Section snippets

Subjects and General Diagnostic Procedures

Characterization of lung β-adrenoceptors was carried out in 11 children with pulmonary hypertension aged four months to 15 years (median, three years) who were considered candidates for surgical repair of congenital heart defects at the Heart Institute, University of Sao Paulo. In these children, small lung specimens for receptor characterization were obtained at the time of routine biopsy procedures in order to evaluate the extent of pulmonary vasoocclusive disorder. At cardiac catheterization

Hemodynamic and Histologic Findings

The mean pulmonary arterial pressure ranged from 33 to 101 mm Hg in children with pulmonary hypertension (Table 1).

In histologic examination of lung biopsy material, increased arterial muscularity was observed in all patients. The medial thickness of terminal bronchiolar, respiratory bronchiolar, and alveolar duct arteries was 21.8 ± 1.8, 22.8 ± 4.3, and 20.1 ± 4.1 percent, respectively.

Intimal lesions compatible with Heath-Edwards grade 2, 3, or 4 were observed in seven patients. The

DISCUSSION

A major limitation of the present study was the relative difficulty in obtaining lung specimens for receptor characterization from children with normal pulmonary pressures. For ethical reasons, we were only able to include in the study subjects from whom lung specimens could be obtained during routine diagnostic or therapeutic procedures.

Information concerning adrenoceptor behavior in pulmonary vaso-occlusive disorders remains limited. Most reports focusing on β-adrenoceptor alterations in lung

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  • Cited by (0)

    Supported by Fundacão de Amparo à Pesquisa do Estado de São Paulo, grant 87/0511-9.

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