The influence of propranolol on the concentration of heme and on the activity of δ-aminolevulinate synthase in monolayers of chick embryo liver cells

The addition of propranolol to monolayers of chick embryo liver cells caused a rapid increase in cellular heme, followed by an equally rapid decrease. Subsequently the concentration of heme rose at a relatively slower rate. About 10 hr after addition of propranolol to the medium a plateau level was reached at ± 35% above control values. Changes in the activity of δ-aminolevulinate synthase (ALAS) were negatively correlated with those of cellular heme. Cycloheximide prevented the above phenomenon. ALAS activity was not clearly correlated with the rapid, partial inhibition of protein synthesis, caused by propranolol. These observations are related to the beneficial influence of administration of hemin or of propranolol to patients with acute attacks of hepatic porphyria.