phosphocreatine and Kidney-Diseases

Noninvasive investigation of renal metabolic changes is possible with 31P-MR, which is characterized by the determination of amounts of "free" phosphorus metabolites and intracellular pH and the possibility of measuring enzyme kinetics by the 31P-MR magnetization transfer method. 31P-MR has been extensively used to monitor such alterations in response to kidney ischemia, in which the ratios of anorganic phosphate to ATP and phosphomonoesters change drastically. The stages of ultrastructural ischemic renal damage can already be accurately classified with reference to a scale of 31P-MR-spectrum-derived renal function predictors. The recent application of MR high-resolution imaging may allow further improvement of organ viability assessment. The clinical use of combined MR imaging and spectroscopy is an essential and imminent step.

Topics: Adenosine Diphosphate; Adenosine Triphosphate; Animals; Energy Metabolism; Humans; Hydrogen-Ion Concentration; Kidney Diseases; Kidney Neoplasms; Kidney Transplantation; Magnetic Resonance Spectroscopy; Organ Preservation; Phosphates; Phosphocreatine; Rats

High prevalence (48%) of insulin resistance (IR) in patients with mild to moderate kidney function reduction, and the potential pathogenetic role of magnesium (Mg) deficiency in IR prompted us to study skeletal muscle free Mg (fMg) concentration in patients with impaired kidney function.. fMg concentration, intracellular pH (pHi) and parameters of energy balance were determined employing 31P NMR spectroscopy in the calf muscle of the dominant leg of 18 healthy controls (C) and 22 patients (P) with decreased kidney function. 10 patients suffered from insulin resistance (IR).. No difference in fMg concentration in skeletal muscle was observed (C: 0.929 +/- 0.075; P: 0.948 +/- 0.062 mmol/l; x +/- SEM). In patients a slight shift of pHi towards acidic values was found (C: 7.036 +/- 0.0.004; P: 7.013 +/- 0.004; p < 0.004), which was even more expressed in IR patients (7.008 +/- 0.005). Serum creatinine levels and creatinine clearance correlated with pHi in the patient's group. Adenosintriphosphate (ATP) to inorganic phosphate (Pi) ratio in skeletal muscle was lower, phosphocreatine (Pcr)/ATP ratio was higher, while that of Pcr/Pi showed only a trend towards an increase in the patient's group.. In patients with reduction of kidney function IR does not associate with a change in skeletal muscle free magnesium concentration, or deficiency in macroergic phosphate levels. Shift in intracellular pH towards acidic values may participate in IR. Decreased activity of Na+/H+ antiporter is suggested. (Fig. 5, Tab. 2, Ref. 22.)

Topics: Adenosine Triphosphate; Creatinine; Energy Metabolism; Female; Humans; Hydrogen-Ion Concentration; Insulin Resistance; Kidney Diseases; Magnesium; Magnetic Resonance Spectroscopy; Male; Middle Aged; Muscle, Skeletal; Phosphates; Phosphocreatine

Topics: Creatinine; Feedback; Humans; Kidney Diseases; Phosphocreatine