EFFECTS OF ALPHA-ADRENERGIC BLOCKADE ON CORONARY BLOOD-FLOW OF DOGS IN HEMORRHAGIC-SHOCK

  • 1 January 1977
    • journal article
    • research article
    • Vol. 4  (4) , 297-303
Abstract
The hypothesis that the vasoconstrictive effects of .alpha.-adrenergic receptors are responsible, at least in part, for the lack of a maximal vasodilatation of coronary arteries during hemorrhagic shock was tested. Open-chested, anesthetized, mongrel dogs were bled so as to reach an arterial pressure level of 44 mm Hg, and were monitored using an electromagnetic, non-cannulating flowmeter. During shock, 2 intracoronary injections were made, 1 of saline, the other of phenoxybenzamine (Dibenzyline). Control dogs had 2 injections of saline. Following phenoxybenzamine, coronary blood flow increased by 32%. Although coronary blood flow may be mainly under local control, the sympathetic nervous system limits maximal coronary vasodilatation during hemorrhagic shock by virtue of activated .alpha.-adrenergic receptors.