AJP - Heart and Circulatory Physiology, Vol 256, Issue 3 828-H831, Copyright © 1989 by American Physiological Society
Proximal and distal dog coronary arteries respond differently to basal EDRF but not to NO
U. Hoeffner, C. Boulanger and P. M. Vanhoutte
Department of Physiology and Biophysics, Mayo Clinic, Rochester, Minnesota 55905.
Experiments were designed to analyze the effects of endothelium-derived
relaxing factor(s) (EDRF; released basally or on stimulation with
acetylcholine) and nitric oxide (NO) on smooth muscle of coronary arteries
of different diameter. During contractions of the bioassay ring evoked with
prostaglandin F2 alpha, the relaxations caused by basal EDRF were greater
in the distal than in the proximal coronary arteries, whereas there was no
difference in response to the EDRF released by acetylcholine. During direct
superfusion, NO caused similar relaxations in proximal and distal coronary
artery rings. Optimal tension, prostaglandin F2 alpha-induced contractions,
and relaxations caused by sodium nitroprusside were comparable in both
preparations. In rings of proximal and distal coronary artery studied in
organ chambers, acetylcholine caused comparable endothelium-dependent,
whereas sodium nitroprusside and NO cause comparable
endothelium-independent relaxations. These experiments indicate a
difference in response of different-sized coronary arteries to basally
released EDRF and suggest that the basally released factor differs from NO.
