ABSTRACT
Media strips of hog carotid artery formed hypoxanthine and inosine during incubation under conditions of normoxia (95% O2, 5% CO2). During anoxia (95% N2, 5% CO2), hypoxanthine increased fivefold and inosine twofold. Stimulation with 124 mM K+ resulted in a twofold increase in hypoxanthine and a threefold increase in inosine. Concurrent with the increase in the concentrations of purine derivatives was a decrease in tissue ATP. Although significant amounts of adenosine were not detected in the medium of incubating artery strips, the following evidence suggests adenosine was formed and rapidly deaminated to inosine: 1) Exogenous adenosine added to the medium of incubating strips was rapidly deaminated to inosine. 2) Exogenous 5'-AMP concentration decreased, whereas adenosine and, subsequently, inosine levels increased during incubation of artery strips. The reaction was specific for 5'-AMP and the data suggest that AMP is dephosphorylated to adenosine. 3) The specific activity of exogenous [U-14C]adenosine added to the medium of incubated strips decreased after 15 min. It is concluded that adenosine is formed in isolated artery strips but is rapidly deaminated to inosine.
Subject(s)
Hypoxanthines/metabolism , Hypoxia/metabolism , Inosine/metabolism , Muscle, Smooth/metabolism , Adenosine/metabolism , Animals , Carotid Arteries/metabolism , In Vitro Techniques , Potassium/metabolism , Swine/metabolismABSTRACT
The results of the present investigation indicate that ISDN infusion following experimental coronary occlusion in anesthetized dogs (1) lowers systemic, cardiac, and pulmonary blood pressures; (2) decreases systemic resistance; (3) has no significant effect on cardiac output, heart rate, and stroke volume; (4) decreases serum CPK levels; and (5) has little effect on blood biochemical parameters. These results suggest that ISDN may have a minimal effect on the ischemic heart by means of a slight decrease in peripheral vascular resistance and systemic blood pressure.
Subject(s)
Coronary Disease/drug therapy , Disease Models, Animal , Isosorbide Dinitrate/therapeutic use , Animals , Blood Pressure/drug effects , Cardiac Output/drug effects , Coronary Disease/blood , Coronary Disease/etiology , Coronary Disease/mortality , Creatine Kinase/blood , Dogs , Drug Evaluation, Preclinical , Male , Vascular Resistance/drug effectsABSTRACT
The effect of sublingual (0.2 mg.) nitroglycerin (TNG) was studied in anesthetized dogs before and after coronary occlusion. Coronary artery occlusion was accomplished by embolization of the circumflex branch of the left coronary artery. TNG was administered before embolization and again at one minute, one, two, and six hours after embolization. TNG treatment did not significantly increase the number of arrhythmias or deaths compared to untreated animals with coronary occlusion. Hemodynamic and blood biochemical parameters were measured 5 to 15 minutes after TNG treatment. At this time of measurement, blood pressures (AO, LV, LA, PA, RV, RA), cardiac output, pulmonary and systemic resistances, and left ventricle work were not significantly different in the TNG-treated group compared to the animals with coronary occlusion but no TNG treatment. In the first five minutes after TNG administration, aortic pressure is reduced. Blood samples withdrawn five minutes after TNG treatment are not significantly different from the untreated animals in PO2, PCO2, pH, glucose, lactate, pyruvate, free fatty acids, LDH, CPK, and SGOT. It is concluded that TNG is not detrimental to animals with acute coronary occlusion and that TNG has a transient, short-duration effect.
