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Enhancement by streptozotocin of O − 2 radical generation by the xanthine oxidase system of pancreatic β‐cells
Author(s) -
Nukatsuka Mamoru,
Sakurai Hiromu,
Yoshimura Yoshiyuki,
Nishida Mikio,
Kawada Jun
Publication year - 1988
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(88)80938-4
Subject(s) - xanthine oxidase , streptozotocin , chemistry , biochemistry , enzyme , diabetes mellitus , endocrinology , biology
Spin‐trapping techniques and electron spin resonance (ESR) spectroscopy were used to study the relationship between the effect of streptozotocin (STZ) on pancreatic β‐cells and free radical formation by these cells. Results showed that STZ enhanced generation of the DMPO‐OH radical adduct, which is a degradation product of the superoxide anion (O − 2 ) in the presence of cellular components, in a hypoxanthine‐xanthine oxidase (XOD) system with a homogenate of β‐cells. This enhancing effect was also observed in a system without cellular components; STZ increased the signal height due to the O − 2 radical in a concentration‐dependent manner and caused a maximum of 150% enhancement at a concentration of 1.5 mM. Thus, STZ seemed to enhance the generation of the O − 2 radical in the XOD system, probably by some mechanism of its interaction with XOD. Pancreatic β‐cells exhibited a high XOD activity and a very low superoxide dismutase activity. Therefore, the present result supports the possibility that the cytotoxic effect of STZ is closely related to free radical generation in pancreatic β‐cells.