Effects of endothelin-1 on coronary microcirculation in isolated beating hearts of rats.
An intravital fluorescence videomicroscope system was used to investigate the pharmacological effects of endothelin-1 (ET-1) on the coronary microcirculation in isolated beating hearts of rats. The heart was perfused by retrograde aortic steady flow with an oxygenated Krebs-Ringer solution containing FITC-dextran. Cumulative injections of ET-1 (1-30 pmol) elicited a dose-dependent increase in perfusion pressure from 52 +/- 15 mm Hg (mean +/- SEM; n = 6) before the ET-1 injection to 104 +/- 23 mm Hg at the ET-1 dose of 30 pmol. A dose-dependent narrowing of microvessels was also observed on a monitor screen. This diffuse vasoconstriction was especially prominent in small arterioles; the maximum vasoconstriction of the smaller arterioles was significantly higher than that of the larger arterioles. These findings suggest that ET-1 may have an important role in governing the coronary resistance and regulating the capillary flow in myocardium.
Homma
S
S
Department of Internal Medicine, University of Tsukuba, Ibaraki, Japan.
Miyauchi
T
T
Goto
K
K
Sugishita
Y
Y
Sato
M
M
Ohshima
N
N
D000818:Animals; D001160:Arterioles / Q000187:drug effects; D003326:Coronary Circulation / Q000187:drug effects*; D003911:Dextrans; D016232:Endothelins / Q000494:pharmacology*; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives; D066298:In Vitro Techniques; D008297:Male; D008833:Microcirculation / Q000187:drug effects; D008856:Microscopy, Fluorescence; D051381:Rats; D011919:Rats, Inbred Strains
D003911:Dextrans; D016232:Endothelins; C015219:fluorescein isothiocyanate dextran; D016650:Fluorescein-5-isothiocyanate