Article: PDF OnlyThuillez C.; Berdeaux, A.; Duhaze, P.; Bonhenry, C.; Giudicelli, J. F.Journal of Cardiovascular Pharmacology: March 1988 - p 344-353 Free Abstract Summary The effects of Bay K 8644, aortic constriction, and a placebo on regional myocardial blood flows (RMBFs) and contractile function (RCF) were compared in three groups of open-chest anesthetized dogs during coronary stenosis. Bay K 8644 was investigated in two doses: 0.1 μg/kg, which exhibited no systemic hemodynamic effect, and 1 μg/kg, which significantly increased arterial pressure. Aortic constriction was performed to raise afterload to the same extent as Bay K 8644 1 μg/kg. As compared with placebo, Bay K 8644 0.1 μg/kg, significantly increased coronary resistance, decreased RMBFs without changing RCF in nonischemic myocardial zones, and affected neither RMBFs nor RCF in ischemic zones. In nonischemic myocardium. Bay K 8644 1 μg/kg increased RMBFs without affecting RCF, whereas aortic constriction did not modify RMBFs but decreased RCF. In ischemic myocardium, both Bay K 8644 1 μg/kg and aortic constriction increased RMBFs but did not affect RCF. Thus, the low dose of Bay K 8644 exerts a direct and selective coronary vasoconstrictor effect that has no deleterious consequences on nonischemic RCF. Despite this intrinsic coronary vasoconstrictor effect, the high dose of Bay K 8644 increases RMBFs and maintains RCF in both ischemic and nonischemic zones in relation with the drug-induced increases in coronary perfusion pressure (both zones) and in contractility (nonischemic zones). © Lippincott-Raven Publishers.