title: [Nitroglycerine promotes myocardial oxygen metabolism and regional cardiac function in vivo].
abstract: OBJECTIVE
  To investigate the effects of nitroglycerine (NTG) on myocardial oxygen metabolism and regional cardiac function in canine hearts with a stable systemic hemodynamics in situ.
  
  
  METHODS
  Eight anesthetized open-chest dogs with flow-limited left anterior descending branch of the coronary artery or left circumflex artery (LCx) stenosis were studied. The percentage of ventricular wall thickening (%WT) was measured with quantitative two-dimensional echocardiography (2DE), myocardial blood flow (MBF) with radiolabeled microspheres and tissue oxygen pressure (tPO(2).) with oxygen-dependent quenching of phosphorescence. 2DE was performed and radiolabeled microspheres and Pd-porphyrin injected in the dogs at rest during intracoronary infusion of 0.3-0.6 mg x kg(-1) x min(-1) of NTG. Myocardial oxygen consumption (MVO(2), ml x min(-1) x 100 g(-1)) was calculated as the multiplication product between the arterio-venous oxygen content difference and MBF, and myocardial O(2) delivery as the product between arterial oxygen content and MBF.
  
  
  RESULTS
  As compared with the baseline, NTG increased %WT and MBF significantly in both normal and ischemic beds (P<0.05). There was a significant increase in MVO(2) during NTG infusion in the ischemic bed (P<0.05) in comparison with that measured at rest. NTG, however, significantly increased the ability of myocardial O(2) delivery in both normal and ischemic beds (P<0.05), therefore tPO(2) was still higher in the ischemic bed during NTG infusion than that at rest (P<0.05). The percentage increment in tPO(2) was significantly greater in the ischemic bed than percentage MBF increment.
  
  
  CONCLUSIONS
  NTG enhances myocardial oxygen concentration in normal and ischemic myocardium and may increase oxygen release to the ischemic myocardium in vivo. NTG may have a positive inotropic effect on regional cardiac function. In addition to direct effect on vascular tone, NTG plays important roles in the cardiovascular system by modulating myocardial oxygen metabolism and contractile function.
authors.affiliation: Department of Caridology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China.
authors.forename: Jian-ping
authors.initials: JP
authors.lastname: Bin
authors.forename: D Elizabeth
authors.initials: DE
authors.lastname: Le
authors.forename: Shao-min
authors.initials: SM
authors.lastname: Chen
authors.forename: Dao-gang
authors.initials: DG
authors.lastname: Zha
authors.forename: Yi-li
authors.initials: YL
authors.lastname: Liu
authors.forename: Sanjiv
authors.initials: S
authors.lastname: Kaul
mesh_terms: D000818:Animals; D004285:Dogs; D004452:Echocardiography; D006439:Hemodynamics; D009206:Myocardium / Q000378:metabolism*; D005996:Nitroglycerin / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000187:drug effects*
chemical_list: D005996:Nitroglycerin