Pulmonary and cardiac beta-adrenoceptor density in vivo in asthmatic subjects

To examine whether there is a primary deficit in beta-adrenoceptor density in asthma, pulmonary and cardiac beta-receptor density was determined in vivo with positron emission tomography (PET) in 10 male asthmatic subjects (36 +/- 8 yr of age) and compared with that in 30 age-matched normal male subjects (36 +/- 8 yr of age). Pulmonary beta-receptor density was 10.3 +/- 1.8 pmol/g tissue for the asthmatic group and 10.9 +/- 1.9 for the normal group. Cardiac beta-receptor density was 9.1 +/- 3.3 pmol/g for the asthmatic group and 8.8 +/- 2.3 pmol/g for the normal group. There was no difference in either pulmonary or cardiac beta-receptor density between the two groups. In addition, an inverse relationship was observed between FEV1 % predicted and pulmonary beta-receptor density in asthmatic subjects. In conclusion, beta-receptor numbers are normal in untreated asthmatic subjects.