Distribution of alloxan-C¹⁴ in islet and other tissues of the toadfish (Opsanus tau)

¹ Department of Anatomy, Western Reserve University School of Medicine, Cleveland, Ohio, Department of Anatomy, University of Minnesota School of Medicine, Minneapolis, Minnesota, and Marine Biological Laboratory, Woods Hole, Massachusetts

These studies on the mechanism by which alloxan selectively destroys the ß cells in the islets of Langerhans have been carried out in the toadfish because the islet tissue in this species is segregated into a discrete mass, separated from the acinar tissue. We have measured the C¹⁴ content of several tissues at various times after intravenous injection of tracer doses of alloxan-2-C¹⁴. The islet C¹⁴ content never exceeded 50% of that of blood and was no greater than that found in many other tissues. Thus the selectivity of alloxan is not due to selective concentration by islet tissue. The distribution of alloxan-2-C¹⁴ was compared with that of d-mannitol-1-H³. A mixture of both isotopic substances was injected and the C¹⁴ and H³ in each tissue determined. The distribution of alloxan-2-C¹⁴ was very similar to that of d-mannitol-1-H³. This suggests that tracer doses of injected alloxan do not enter islet cells but remain in the extracellular compartment, and that the ß-cell membrane may be a primary site of alloxan action.

Note:
With the Technical Assistance of James A. Jackson

Key Words: alloxan • alloxan diabetes • ßbeta; cell • islets of Langerhans • cell membrane • extracellular space • permeability diabetes • cytotoxin • alloxan, mechanism of action

Submitted on November 7, 1963