AJP - Heart and Circulatory Physiology, Vol 260, Issue 3 967-H972, Copyright © 1991 by American Physiological Society
A new relaxing factor in supernatant of incubated rat peritoneal neutrophils
K. Kadota, Y. Yui, R. Hattori, H. Uchizumi and C. Kawai
Department of Internal Medicine, Faculty of Medicine, Kyoto University, Japan.
It was found that when rat peritoneal neutrophils were added to an organ
bath, they released an unstable vasoactive substance designated as
neutrophil-derived relaxing factor (NDRF), which is similar to
endothelium-derived relaxing factor. Besides NDRF, a more stable (activity
maintained for at least 7 days at -80 degrees C) relaxing factor was found
to be generated in the supernatant after the incubation of rat peritoneal
neutrophils in buffer. This supernatant relaxing factor (SRF) induced an
increase in the guanosine 3',5'-cyclic monophosphate content of aortic
strips. Its relaxing activity was potentiated by superoxide dismutase. It
was inhibited by hemoglobin, hydroquinone, or methylene blue but not by
catalase or mannitol. Preincubation of polymorphonuclear neutrophils with
aspirin, quinacrine, metyrapone, or AA-861 had no effect on the relaxing
activity of SRF. L-Arginine dose dependently increased the relaxing
activity of SRF, whereas NG-monomethyl-L-arginine (L-NMMA) decreased it,
and this decrease was reversed by L-arginine. In contrast, neither
L-arginine nor L-NMMA affected the relaxing activity of NDRF. These data
suggest that SRF may represent a relaxing factor that is synthesized de
novo from L-arginine.
