Itoya M, Mallet R T, Gao Z P, Williams A G, Downey H F
Department of Integrative Physiology, University of North Texas Health Science Center at Fort Worth 76107-2699, USA.
Am J Physiol. 1996 Jul;271(1 Pt 2):H320-8. doi: 10.1152/ajpheart.1996.271.1.H320.
This study was conducted to determine if mechanisms that reduce right coronary (RC) blood flow (RCBF) and right ventricular (RV) oxygen consumption (MVO2) during moderate RC hypotension preserve RV high-energy phosphates. RC arteries of anesthetized dogs were cannulated and perfused with arterial blood supplied by a pressurized extracorporeal circuit. RC perfusion pressure (RCPP) was either kept constant at 100 mmHg or reduced to 60 or 30 mmHg for 20 min followed by a freeze-clamp biopsy of RV. Left ventricular (LV) biopsy was also performed to compare energy metabolism between RV and LV.RCBF and MVO2 significantly decreased when RCPP was reduced to 60 mmHg, but RV segment shortening (%SS) was unchanged; ATP, creating phosphate (CrP) and phosphorylation state of CrP ([CrP]/[Cr][Pi]) did not differ from control values. RV %SS, CrP, and phosphorylation state fell markedly at 30 mmHg RCPP. At 100 mmHg RCPP, CrP phosphorylation state in RV was only 35% of that in LV. These results indicate that RV increases its energetic efficiency without significant changes in high-energy phosphates or CrP phosphorylation state during moderate RC hypotension. Furthermore, the RV myocardium maintains a much lower energy level than LV myocardium, commensurate with its lower energy requirements.
本研究旨在确定在中度右冠状动脉低血压期间减少右冠状动脉（RC）血流（RCBF）和右心室（RV）氧消耗（MVO2）的机制是否能维持RV的高能磷酸盐水平。对麻醉犬的RC动脉进行插管，并由加压体外循环供应的动脉血进行灌注。RC灌注压（RCPP）要么保持在100 mmHg恒定，要么降至60或30 mmHg持续20分钟，随后对RV进行冷冻钳夹活检。还进行了左心室（LV）活检以比较RV和LV之间的能量代谢。当RCPP降至60 mmHg时，RCBF和MVO2显著降低，但RV节段缩短率（%SS）未改变；ATP、磷酸肌酸（CrP）和CrP的磷酸化状态（[CrP]/[Cr][Pi]）与对照值无差异。在30 mmHg RCPP时，RV %SS、CrP和磷酸化状态显著下降。在100 mmHg RCPP时，RV中CrP的磷酸化状态仅为LV中的35%。这些结果表明，在中度RC低血压期间，RV在高能磷酸盐或CrP磷酸化状态无显著变化的情况下提高了其能量效率。此外，RV心肌维持的能量水平远低于LV心肌，与其较低的能量需求相称。
