Urinary Porphyrins in Experimental Lead Poisoning

Abstract

THE porphyrin excreted in the urine of normal and of experimentally lead-poisoned rabbits has long been regarded as coproporphyrin. The recent development¹ of a chromatographic method for the separation of porphyrins according to the number of carboxyl functions has already revealed 3- and 5-carboxyl porphyrins in a number of pathological urines. We have investigated the urinary ether-soluble porphyrins of rabbits which received loading doses of 13.7 mgm./kgm. of lead chloride intravenously, and were then fed on a diet containing 250 p.p.m. of lead carbonate for periods up to four months. Urine was collected over periods of three days and preserved with toluene. The porphyrins were extracted with ether and acetic acid by the technique previously used by one of us², and estimated in 0.25 per cent hydrochloric acid with a Unicam spectrophotometer (λ = 401 mµ). They were chromatographed on paper at 7° C. by the method of Nicholas and Rimington¹ to characterize the porphyrins present.