Biomaterial Database

Myocardial blood flow and O2-supply following dextran-haemodilution and methaemoglobinaemia in the dog. 1979

G P Biro, and D Beresford-Kroeger

The adequacy of oxygen-supply to the left ventricular myocardium was compared in anaesthetised dogs following: a) isovolaemic haemodilution with Dextran 70 (to haematocrit = 20 +/- 2%), b) the acute induction of methaemoglobinaemia (to methaemoglobin-concentration = 53 +/- 7%), bu subjecting them to an exchange-transfusion with methaemoglobin-containing erythrocytes in dextran) and c) a control exchange-transfusion with normal homologous erythrocytes in dextran. Myocardial oxygen-supply was assessed by the measurement of myocardial blood flow (using 15 +/- 5 micron microspheres) and of the PO2 in coronary sinus blood. In dextran-haemodiluted dogs, mean myocardial blood flow was 92% greater than in the control group, allowing the maintenance of normal coronary sinus PO2. In the methaemoglobinaemic group, flow was only 15% greater than in the control group; because oxygen-capacity was halved in this group, myocardial oxygen supply was impaired and coronary sinus PO2 fell. Infusions of isoproterenol (0.1 microgram . kg-1 . min-1) produced similar myocardial flow-increments in the haemodiluted and control groups with similar transmural distribution. In the methaemoglobinaemic group, however, the subendocardial flow-increment was reduced, in association with a further reduction in coronary sinus PO2 and an attenuated contractile response to the drug. These findings suggest that the rheological effects of haemodilution play an important role in the maintenance of myocardial oxygen-supply, but in significant methaemoglobinaemia, the oxygen supply of the myocardium may be severely curtailed.

UI	MeSH Term	Description	Entries
D007545	Isoproterenol	Isopropyl analog of EPINEPHRINE; beta-sympathomimetic that acts on the heart, bronchi, skeletal muscle, alimentary tract, etc. It is used mainly as bronchodilator and heart stimulant.	Isoprenaline,Isopropylarterenol,4-(1-Hydroxy-2-((1-methylethyl)amino)ethyl)-1,2-benzenediol,Euspiran,Isadrin,Isadrine,Isopropyl Noradrenaline,Isopropylnoradrenaline,Isopropylnorepinephrine,Isoproterenol Hydrochloride,Isoproterenol Sulfate,Isuprel,Izadrin,Norisodrine,Novodrin,Hydrochloride, Isoproterenol,Noradrenaline, Isopropyl,Sulfate, Isoproterenol
D008297	Male		Males
D008708	Methemoglobinemia	The presence of methemoglobin in the blood, resulting in cyanosis. A small amount of methemoglobin is present in the blood normally, but injury or toxic agents convert a larger proportion of hemoglobin into methemoglobin, which does not function reversibly as an oxygen carrier. Methemoglobinemia may be due to a defect in the enzyme NADH methemoglobin reductase (an autosomal recessive trait) or to an abnormality in hemoglobin M (an autosomal dominant trait). (Dorland, 27th ed)	Methemoglobinemias
D009206	Myocardium	The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.	Muscle, Cardiac,Muscle, Heart,Cardiac Muscle,Myocardia,Cardiac Muscles,Heart Muscle,Heart Muscles,Muscles, Cardiac,Muscles, Heart
D010100	Oxygen	An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.	Dioxygen,Oxygen-16,Oxygen 16
D010313	Partial Pressure	The pressure that would be exerted by one component of a mixture of gases if it were present alone in a container. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Partial Pressures,Pressure, Partial,Pressures, Partial
D003326	Coronary Circulation	The circulation of blood through the CORONARY VESSELS of the HEART.	Circulation, Coronary
D003331	Coronary Vessels	The veins and arteries of the HEART.	Coronary Arteries,Sinus Node Artery,Coronary Veins,Arteries, Coronary,Arteries, Sinus Node,Artery, Coronary,Artery, Sinus Node,Coronary Artery,Coronary Vein,Coronary Vessel,Sinus Node Arteries,Vein, Coronary,Veins, Coronary,Vessel, Coronary,Vessels, Coronary
D003911	Dextrans	A group of glucose polymers made by certain bacteria. Dextrans are used therapeutically as plasma volume expanders and anticoagulants. They are also commonly used in biological experimentation and in industry for a wide variety of purposes.	Dextran,Dextran 40,Dextran 40000,Dextran 70,Dextran 75,Dextran 80,Dextran B-1355,Dextran B-1355-S,Dextran B1355,Dextran B512,Dextran Derivatives,Dextran M 70,Dextran T 70,Dextran T-40,Dextran T-500,Hemodex,Hyskon,Infukoll,Macrodex,Polyglucin,Promit,Rheodextran,Rheoisodex,Rheomacrodex,Rheopolyglucin,Rondex,Saviosol,Dextran B 1355,Dextran B 1355 S,Dextran T 40,Dextran T 500
D004285	Dogs	The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)	Canis familiaris,Dog