DEPENDENCE OF ACCUMULATION OF 13-NH3 BY MYOCARDIUM ON METABOLIC FACTORS AND ITS IMPLICATIONS FOR QUANTITATIVE ASSESSMENT OF PERFUSION
DEPENDENCE OF ACCUMULATION OF 13-NH3 BY MYOCARDIUM ON METABOLIC FACTORS AND ITS IMPLICATIONS FOR QUANTITATIVE ASSESSMENT OF PERFUSION
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DOI：
10.1161/01.cir.61.1.34
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发表时间：
1980-01-01
期刊：
影响因子：
37.8
通讯作者：
SOBEL, BE
中科院分区：
文献类型：
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作者：
BERGMANN, SR;HACK, S;SOBEL, BE
残余部分，即大剂量注射13n标记氨NH3后，心肌提取并保留的示踪剂的部分。在选择性和独立控制血流和心脏代谢的条件下，研究了离体灌注兔心脏中NH4+的含量。该正电子发射示踪剂的残留分数和间隙（定义为消除隔离示踪剂所需的半衰期[t1/2]）通过同步检测进行监测和量化。用改良的Krebs-Henseleit缓冲液（KH）或富含水洗绵羊红细胞（KH- rbc）的KH灌注心脏以增加o2携带能力。在13颗经KH灌注的心脏中，当流量从4.2 ml/g / min的对照速率减少75%时，13N计数的残余分数（Res Fx）没有显著改变（Res Fx = 17.9 +-）。2.7%;的意思。+ -。平均标准误差为1.2 ml/g / min (Res Fx = 18.4 +-。1.2%， NS[无统计学意义]。13N的清除速度更快，因为t1/2从36 .+-减小。5分钟至15分钟。3 min （P < 0.01）。在12颗灌注了KH-RBC的心脏中，尽管血流从1.4 ml/g / min到0.3 ml/g / min减少了75%（控制值：Res Fx = 54.6 +-），但明显缺血，但Res Fx和t1/2没有改变。2.4%, t1/2 = 41 +-。6分钟;低流量值：Res Fx = 58.1 .+-。4.4%, t1/2 = 35。10分钟，NS)。另外4个心脏灌注0.02 mg/ml蛋氨酸亚砜胺（一种谷氨酰胺合成酶抑制剂）的KH-RBC，与抑制前值相比，心肌保留13N计数减少了60%，心肌清除率延长。心肌对13N活性的保留和清除在相当程度上明显受心肌代谢状态的影响。示踪剂的提取和保留与血流本身之间的关系是复杂的，并且排除了通过心肌隔离的示踪剂量直接估计灌注的可能性。
The residual fraction, the fraction of tracer extracted and retained by the myocardium after a bolus injection of 13N-labeled ammonia NH3 .dblarw. NH4+, was studied in isolated perfused rabbit hearts under conditions in which flow and cardiac metabolism could be selectively and independently controlled. Residual fraction and clearance (defined as the half-time [t1/2] required for elimination of sequestered tracer) of this positron-emitting tracer were monitored and quantified by coincident detection. Hearts were perfused with modified Krebs-Henseleit buffer alone (KH) or KH enriched with washed sheep erythrocytes (KH-RBC) to augment O2-carrying capacity. In 13 hearts perfused with KH, the residual fraction (Res Fx) of 13N counts was not altered significantly when flow was decreased by 75% from a control rate of 4.2 ml/g per min (Res Fx = 17.9 .+-. 2.7%; mean .+-. standard error of the mean) to 1.2 ml/g per min (Res Fx = 18.4 .+-. 1.2%, NS [not significant]. Clearance of 13N was faster because t1/2 decreased from 36 .+-. 5 min to 15 .+-. 3 min (P < 0.01). In 12 hearts perfused with KH-RBC, Res Fx and t1/2 were not altered despite marked ischemia when flow was diminished by 75% from control flow of 1.4 to 0.3 ml/g per min (control values: Res Fx = 54.6 .+-. 2.4%, t1/2 = 41 .+-. 6 min; low flow values: Res Fx = 58.1 .+-. 4.4%, t1/2 = 35 .+-. 10 min, NS). In 4 additional hearts perfused with KH-RBC with 0.02 mg/ml of methionine sulfoximine, a glutamine synthetase inhibitor, myocardial retention of 13N counts was reduced by > 60% and myocardial clearance was prolonged compared to pre-inhibition values. The retention and clearance of 13N activity by myocardium are evidently influenced to a considerable extent by the metabolic state of the myocardium. Relationships between extraction and retention of tracer and flow per se are complex and preclude direct estimation of perfusion from the amount of tracer sequestered by the myocardium.