The effects of tolazoline on the distribution of cardiac output in normoxemic and hypoxemic lambs.
We measured cardiac output and its distribution (microspheres), blood gases and pH, heart rate, and pulmonary and aortic pressures in three groups of 1- to 3-day-old lambs. Group I consisted of six animals who had these measurements made during both control (normoxemic) and hypoxemic (PaO2 25 +/- 3 mm Hg) periods. Hypoxemia increased the pulmonary artery pressure 70% (p less than 0.01). This elevation in pulmonary arterial pressure lasted as long as the animals were hypoxemic (90 min). Hypoxemia had no effect on cardiac output, mean systemic arterial pressure, heart rate, or the rate-pressure product of the left ventricle. Blood flow to the heart increased an average of 228% (p less than 0.05); flow to the brain increased 233% (p less than 0.05); flow to the skin decreased 35% (p less than 0.05) after 60 and 90 min of hypoxemia. Blood flow to the remaining organs was uneffected by hypoxemia. Group II consisted of four animals who were given 1, 5, and 10 mg/kg/h of tolazoline (Priscoline) intravenously while normoxemic. There was no effect on the pulmonary arterial pressures or blood gases and pH. Tolazoline (5 and 10 mg/kg/h) reduced systemic arterial pressures an average of 22% (p less than 0.05). Tolazoline (1 mg/kg/h) reduced blood flow to the spleen 48% and that to the brain by 20% and increased flow to the body 32% (p less than 0.05). Five mg/kg/h of tolazoline decreased renal and brain blood flow 35 and 20%, respectively (p less than 0.05) while that to the body and liver increased 26 and 48% (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
D000818:Animals; D001775:Blood Circulation / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D000860:Hypoxia / Q000188:drug therapy* / Q000503:physiopathology; D008863:Microspheres; D011659:Pulmonary Gas Exchange; D012039:Regional Blood Flow / Q000187:drug effects; D012756:Sheep; D014043:Tolazoline / Q000494:pharmacology* / Q000627:therapeutic use
D014043:Tolazoline