Lung release of HIPDM: a new index of lung dysfunction for clinical and experimental studies.

Lung uptake,metabolism and release of amines has been experimentally documented. We studied in rabbit and man the lung kinetics of radioiodinated N-N-N'-trimethyl-N--(2-hydroxy-3-methyl-5-iodobenzyl) -1,3-propanediamine (HIPDM) in rabbits,after i.v.injection, 95% of HIPDM is kept within the lungs and is then released with a mean time (E) of several hours as assessed both in vivo, by gamma camera external counting (n=5,t=7.0hrs), and in vitro by measuring activity in lung homogenates at various times after injection (n=56,.t=7.6 hrs). In 10 healthy non smoking subjects t was 6.4+/-1 hrs, whereas it was 12.1±2hrs in 10 asymptomatic smokers with normal pulmonary function tests. Preliminary clinical studies showed that HIPDM lung release is delayed in non smoking patients with primary pulmonary hypertension(n=4,E=U.5t2hrs) and to a greater extent L adult respiratory distress syndrome (n-4;E-25 8+5 hrs) whereas it was not significantly affected in cardiogenic pulmonary edema (n=4; t=8. 8±2 hrs). Hence both smoke exposure and injury to the lung microcir- culation may impair HIPDM lung kinetics. HIPDM external counting may therefore provide a new index of lung dysfunc- tion in man. Rabbit can be used as a model to evaluate HIPDM lung kinetAcs in experimentally induced lung injury.