Abstract
Uptake of catecholamines by adrenergic fibers was tested in isolated rat irises using the histochemical formaldehyde condensation technique. Minimum concentration in medium for detectable uptake was 0.5 µg/ml for the naturally-occurring catecholamines norepinephrine, epinephrine and dopamine. Adenosine mono-, di-, or triphosphate in minimum concentration of 0.01 µg/ml was required for amine uptake. Parallel specific chemical analyses confirmed the uptake of norepinephrine and epinephrine shown histochemically.