Halothane, but not isoflurane or enflurane, protects against spontaneous and epinephrine-exacerbated acute thrombus formation in stenosed dog coronary arteries.
Occlusive platelet thrombi periodically form in mechanically stenosed dog coronary arteries producing cyclical blood flow reductions occurring over 4-7 min. Cyclical coronary flow reductions are exacerbated by IV epinephrine 0.4 microgram.kg-1.min-1 for 15 min. These flow reductions can be abolished by known inhibitors of platelet function. This study assesses the effect of halothane, isoflurane, and enflurane on spontaneous- and epinephrine-exacerbated cyclical coronary flow reductions. Twenty-three open-chest dogs [1% halothane (n = 5), 0.5% halothane (n = 5), 0.25% halothane (n = 3), 1.5% isoflurane (n = 5), and 2.0% enflurane (n = 5)] with a mechanically stenosed coronary artery showed cyclical blood flow reductions. With 1.0% halothane administration, spontaneous cyclical blood flow reductions were abolished (n = 5), whereas during administration of isoflurane 1.5% (n = 5) and enflurane 2.0% (n = 5) cyclical flow reductions and myocardial ischemia continued. Subsequent administration of halothane in the isoflurane and enflurane groups showed abolition of coronary flow reductions in all animals (n = 10). In eight animals a 15-min epinephrine infusion (0.4 microgram.kg-1.min-1) was given following a control period and again following abolition of coronary flow reductions by halothane 0.5% (n = 5) and halothane 0.25% (n = 3). The magnitude of cyclical blood flow reductions (difference between initial and final coronary flow level of each flow reduction) changed from 52 +/- 11 to 61 +/- 12 ml/min (NS), and frequency increased from 0.37 to 0.57/min (P less than 0.05, n = 8) during epinephrine infusion.(ABSTRACT TRUNCATED AT 250 WORDS)
Bertha
B G
BG
Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota 55905.
Folts
J D
JD
Nugent
M
M
Rusy
B F
BF
D000818:Animals; D003326:Coronary Circulation / Q000187:drug effects; D003327:Coronary Disease / Q000097:blood* / Q000503:physiopathology / Q000517:prevention & control*; D003328:Coronary Thrombosis / Q000139:chemically induced / Q000517:prevention & control*; D004285:Dogs; D004737:Enflurane / Q000494:pharmacology*; D004837:Epinephrine / Q000037:antagonists & inhibitors*; D005260:Female; D006221:Halothane / Q000494:pharmacology*; D007530:Isoflurane / Q000494:pharmacology*; D008297:Male
D004737:Enflurane; D007530:Isoflurane; D006221:Halothane; D004837:Epinephrine