AJP - Heart and Circulatory Physiology, Vol 256, Issue 2 468-H471, Copyright © 1989 by American Physiological Society
Lipoxins A4 and B4 dilate cerebral arterioles of newborn pigs
D. W. Busija, W. Armstead, C. W. Leffler and R. Mirro
Department of Physiology and Biophysics, University of Tennessee, Memphis 38163.
We determined the effects of lipoxins A4 and B4 on the cerebral
microcirculation of neonatal pigs and whether vascular responses were
modulated by prostanoids. Pial arteriolar diameters were determined using a
closed cranial window and intravital microscopy. Before lipoxin A4
application, arteriolar diameter was 143 +/- 6 microns (means +/- SE).
Topical application of lipoxin A4 increased the diameter to 160 +/- 7
microns at 0.1 ng/ml, 167 +/- 7 microns at 1 ng/ml, and 173 +/- 7 microns
at 10 ng/ml (n = 9). Before application of lipoxin B4, arteriolar diameter
was 146 +/- 7 microns. Topical application of lipoxin B4 increased the
diameter to 165 +/- 7, 169 +/- 6, and 175 +/- 6 microns at 0.1, 1, and 10
ng/ml (n = 9), respectively. Intravenous injection of indomethacin (5
mg/kg) or vehicle did not affect these responses. Levels of prostaglandins
E2 and F2 alpha in cerebrospinal fluid (measured by radioimmunoassay) did
not increase in response to lipoxins. We conclude that lipoxins are dilator
stimuli in the cerebral circulation and that prostanoids do not mediate
these responses.
