BACKGROUND & AIMS:
Using 31phosphorus magnetic resonance spectroscopy (31P-MRS) and surface coils, we noninvasively assessed the intracellular changes in delayed skin flaps of the high-energy phosphometabolites, ATP and phosphocreatine, which are basic energy sources of living cells. In 5 rats, a 3.5 x 7.5 cm bipedicled skin flap was elevated from the dorsum and its caudal base divided after a delay period of 2 weeks. MRS spectra were collected at four timesimmediately, 1 week and 2 weeks after elevation of the bipedicled flap, and 18 hours after division of its caudal base.
From the spectra, we calculated the intracellular pH and the following ratiosPi/PCr, PCr/(PCr + Pi), ATP/(PCr + Pi) (PCr, phosphocreatine; Pi, inorganic phosphate; ATP, adenosine triphosphate). As an undelayed control group, cranially based skin flaps of the same size were elevated in another 5 rats, and MRS spectra were obtained 18 hours later. The length of the surviving area was longer in the delayed flaps than in the undelayed flaps. Intracellular pH and ATP/(PCr + Pi) showed no significant alteration in the delayed skin flaps, not only during the delay period but also after conversion of the flaps into cranially based flaps by division of their caudal base. In contrast, PCr/(PCr + Pi) decreased with each surgical procedure (bipedicled flap elevation and base division). Compared with the necrotic distal portion of the undelayed flaps, the surviving distal portion of the delayed flaps had higher levels of intracellular pH and ATP/(PCr + Pi) and lower levels of PCr/(PCr + Pi). Intracellular pH and ATP/(PCr + Pi) showed a strong correlation with the viability of the delayed and undelayed skin flaps, and they can be prognostic indices for predicting the fate of skin flaps. The reason the surviving distal portions of the delayed flaps maintained their level of ATP despite the low intracellular level of PCr may be that the accumulation of mitochondrial creatine kinase enhances the so-called 'energy transport' function of the creatine kinase/phosphocreatine system.
背景与目标:
使用31磷磁共振波谱 (31P-MRS) 和表面线圈,我们无创地评估了高能磷酸代谢物,ATP和磷酸肌酸 (它们是活细胞的基本能量来源) 的延迟皮瓣的细胞内变化。在5只大鼠中,从背部抬高3.5 x 7.5厘米双蒂皮瓣,并在2周的延迟期后将其尾基分开。在双蒂皮瓣抬高后1周和2周以及尾基分裂后18小时立即收集4次MRS光谱。
从光谱中,我们计算了细胞内pH和以下比率Pi/PCr,PCr/(PCr Pi),ATP/(PCr + Pi) (PCr,磷酸肌酸; Pi,无机磷酸盐; ATP,三磷酸腺苷)。作为不延迟的对照组,在另外5只大鼠中升高了相同大小的基于颅骨的皮瓣,并在18小时后获得了MRS光谱。延迟皮瓣中存活区域的长度比未延迟皮瓣中的更长。细胞内pH和ATP/(PCr Pi) 在延迟的皮瓣中没有显示出明显的变化,不仅在延迟期间,而且在通过将其尾基分割将皮瓣转化为基于颅骨的皮瓣之后。相反,每次手术 (双蒂皮瓣抬高和基底分裂) 时,PCr/(PCr Pi) 均降低。与未延迟皮瓣的坏死远端部分相比,存活的延迟皮瓣的远端部分具有较高的细胞内pH和ATP/(PCr Pi) 水平和较低的PCr/(PCr Pi) 水平。细胞内pH和ATP/(PCr Pi) 与延迟和未延迟皮瓣的生存能力有很强的相关性,它们可以作为预测皮瓣命运的预后指标。尽管细胞内PCr水平较低,但存活的延迟皮瓣远端部分仍保持其ATP水平的原因可能是线粒体肌酸激酶的积累增强了肌酸激酶/磷酸肌酸系统的所谓 “能量传输” 功能。