Studies of myocardial protection in the immature heart. I. Enhanced tolerance of immature versus adult myocardium to global ischemia with reference to metabolic differences

• Published in: The Journal of thoracic and cardiovascular surgery Vol. 100; no. 6; pp. 879 - 887
• Main Authors: Julia, PL, Kofsky, ER, Buckberg, GD, Young, HH, Bugyi, HI
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA AATS/WTSA 01.12.1990; Elsevier
• Subjects: Adenosine Triphosphate - metabolism; Aging - metabolism; Aging - physiology; Amino Acids - metabolism; Animals; Aorta; Biological and medical sciences; Body Water - metabolism; Citric Acid Cycle; Constriction; Coronary Circulation; Coronary Disease - complications; Coronary Disease - metabolism; Coronary Disease - physiopathology; Dogs; Glycogen - metabolism; Heart - physiopathology; Medical sciences; Myocardium - metabolism; Phosphocreatine - metabolism; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Surgery of the heart; Ventricular Fibrillation - etiology; Ventricular Fibrillation - physiopathology; Ventricular Fibrillation - therapy; Ventricular Function, Left; Human; Fissipedia; Carnivora; Phosphorylation; Tolerance; Cardiovascular disease; Experimental study; Metabolism; Transamination; Vertebrata; Mammalia; Clamping(surgery); Newborn; Ischemia; Aminoacid; Animal; Surgery; Myocardium; Adult; Aorta; Left ventricle performance; Dog; Comparative study
• ISSN: 0022-5223; 1097-685X
• DOI: 10.1016/s0022-5223(19)36831-x

This study compares the metabolism and functional responses of adult and immature hearts to a standard ischemic insult. Ten adult dogs (25 to 27 kg) and 10 puppies (6 to 10 weeks old) underwent 45 minutes of aortic clamping on bypass. Preoperative and postoperative ventricular performance (Starling curves), biochemical factors, and water content were measured. Global ischemia in adults produced a 30% mortality rate (3/10) and low output syndrome in survivors (33% recovery of stroke work index). Conversely, all puppies survived and stroke work index returned to 85% of control, with less edema developing (0.4% versus 2% water gain, p less than 0.05). Puppies expended comparable glycogen stores but used more glutamate (15.4 versus 8.6 mumol/gm dry weight), produced more alanine (18.9 versus 6.4 mumol, p less than 0.05), succinate (19 versus 8.2 mumol, p less than 0.05), and malate (2.6 versus 0.15 mumol, p less than 0.05) during ischemia, and recovered better postischemic aerobic metabolism (410 versus 255 nmol tissue pyruvate, p less than 0.05). We conclude that tolerance of immature hearts to ischemia is related to amino acid utilization by transamination and increased substrate level phosphorylation, as occurring in diving mammals, suggesting retention of intrautero adaptive mechanisms.