Uptake of radiosulfate in the islets of Langerhans of mice

562

LETTERS

TO

THE

EDITORS

ACKNOWLEDGEMENT The author this investigation.

wishes

to thank

Dr.

William

Sleator

for

his guidaace

throughout

REFERENCES 1. BENDALL, J. R., Proc. Roy. Sot. B142,409 (1954). 2. GOODALL, M. C., AND SZENT-GY~RGYI, A. G., Nature 1’73, 84 (1953). 3. LORaND, L., ~Ckt’U?X 173, 1181 (1953). 4. FRIES, E. T., Arch. Biochem. and Biophys. 61, 17 (1954). 5. BENDALL: J. R., J. Physiol. 121, 232 (1953). 6. SZENT-GY~RGYI, A. Biol. Bull. 98, 140 (1949). SHIZUO WATANABE Department oj Physiology, Washington University School Of Nedicine , Saint Louis, Missouri Received December %, 1954

Uptake

of Radiosulfate

in the

Islets

of Langerhans

of Mice

Ten adult mice were injected with 30 pcuries (&/g. of radiosulfate and killed after 6, 24, 48, 96, or 192 hr. The pancreas of each animal was then immediately fixed in pure methanol for 24 hr., passed through xylene, and embedded in paraffin and cut in 4 p sections which were exposed on Agfa Printon R film for 49 days. The film was developed in Kodak D76 for 6 min. at +lS”C., fixed, washed and dried, and compared with the section which was stained with hemalumeosin. The islets of Langerhans were usually clearly visible on the autoradiographs. There was a relatively high uptake of radiosulfate, compared to the exocrine part of pancreas, 6 and 24 hr. after injection (see Fig. 1). In the 96-hr. specimens

FIG. 1. Part of a histological section of pancreas, corresponding autoradiograph (bottom, dark parts islet t.aking up considerable amounts of radioactive small strongly radioactive area of the autoradiograph and the perivascular connective tissue.

magnified 41 times, and the indicate radioactivity). An sulfate is clearly seen. The corresponds to a vessel

LETTERS

TO

THE

563

EDITORS

FIG. 2. Time-concentration curves of radioactivity in the islets (I), the exocrine part (E), and blood (B), based upon grain countings in the emulsions. Ordinate: grains per 8.6 sq. p of emulsion. Abscissa: time in days after injection of radiosulfate.

the amounts of radiosulfate appeared about equal in the exocrine and endocrine parts. The 48.hr. specimens which were not of good quality showed an intermediate position. The 192-hr. specimens exhibited about the same density in the islets as in the surrounding exocrine gland. Figure 2 is a graphic representation of the radiosulfate concentrations from grain countings. The error in a single estimation of this kind is judged to 16%. These facts indicate higher uptake and more rapid metabolism of sulfate in the endocrine than in the exocrine part. In an earlier work (1) it was stated that the islets of an adult rabbit contained less radiosulfate than the exocrine part after 48 hr. We have some new material from adult and infantile rabbits after 48 hr. showing the same or less uptake of the islets. This may be related to the species or may be due to other causes. The available evidence so far [e.g. that of BostrGm (a)] indicates that high uptake of radiosulfate in soft tissues is usually related to the presence of mucopolysaccharides in these tissues. Nothing can, however, be said at present about the nature and funct.ion of the compound turning over radiosulfate in the islets of Langerhans. REFERENCES

1. ODEBLAD, 2. BOSTR~M,

E., AND BOSTR~M, H., H., Arkiv Kemi 6, No.

Isotope Research Laboratory, Women's f%nic of Karolinsh’a Sabbatsberg Hospital, Stockholm, Sweden Received December 6, 1964

Znstitute,

Acta Pathol. Microbial. 5, 43 (1953).

Stand. &EN ERIK

31, 339 (1952). ORHAGEN ODEBLAD