AJP - Cell Physiology, Vol 255, Issue 4 C452-C458, Copyright © 1988 by American Physiological Society
Development of a new fluorescent angiotensin II probe
V. Fatigati and M. J. Peach
Department of Pharmacology, University of Virginia School of Medicine, Charlottesville 22908.
Angiotensin II (ANG II) was conjugated to polystyrene Latex fluorescent
microspheres (0.5 or 0.05 micron diam) with carbodiimide. Biological
activity of the ANG II-conjugated microspheres (ANG II microspheres) was
assessed in dispersed hepatocytes. The 0.05 micron ANG II microspheres
inhibited glucagon-stimulated adenosine 3',5'-cyclic monophosphate
accumulation and stimulated phosphorylase activity in hepatocytes, whereas
the 0.5 micron ANG II microspheres only stimulated phosphorylase activity.
The biological activity of the ANG II microspheres was caused by the
conjugated ANG II and not by "free" ANG II associated with the spheres or
by trypsin-like activity of hepatocytes causing release of ANG II from the
microspheres. Binding of 0.05 micron ANG II to hepatocytes was readily
observed with fluorescence microscopy. Little, if any, binding was observed
with microspheres without conjugated ANG II. This fluorescent preparation
of ANG II may have great utility in the study of receptor behavior after
binding in individual cells.
