THE HEMODYNAMIC EFFECTS OF HYPOTENSIVE DRUGS IN MAN. II. DIHYDROERGOCORNINE 1

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Abstract
Dihydroergocornine (DHO) admd. intraven. in man produced the following hemodynamic effects: Vasopressor responses to blood-pressure-lowering procedures (Valsalva maneuver, upright tilting), and to the immersion of a hand in iced water (cold test) were inhibited or abolished. Skin temp. in the digits exhibited significant increases in a warm, but not in a cool environment. Digital pulse volumes increased, and reflex vasoconstrictor responses to "noxious" stimuli usually decreased. Blood flow through the forearm and leg frequently increased as the arterial pressure fell, but it sometimes decreased or remained unchanged. Blood flow through the hepatic-portal circuit also varied in different patients, occasionally remaining at control levels early in the hypotensive response, but usually becoming reduced proportionately more than the arterial pressure. The variability of the responses in blood flow in the limbs and in the hepatic-portal region suggests that the drug may have multiple and opposing effects, or that after it has been given, certain counteracting vasoconstrictor mechanisms may become activated. Renal blood flow decreased initially, but in 3 of 5 patients it later returned to control levels. Glomerular filtration rate paralleled renal blood flow. Hence, there was little change in the filtration fraction. Oliguria occurred and persisted even when renal plasma flow and glomerular filtration rate returned to control values. Therefore, the oliguria appeared to be secondary to increased tubular reabsorption of water. The fall in arterial pressure in the supine position was accompanied by no change or a slight increase in cardiac output. Total peripheral resistance, therefore, was reduced. The bradycardia accompanying the hypotensive response was not abolished by atropine. Venous congestion by cuffs high on the extremities could precipitate collapse in supine patients who had received DHO. "Vascular distensibility" in the limbs usually decreased, while venous pressure in the arm rose. Arterial pulsations became more prominent in the venous pressure recordings taken from the antecubital vein. The alkaloids, dihydroergocornine and dihydroergokryptine, opposed only slightly the effects of epinephrin on the arterial pressure and heart rate of man.