phosphorus-radioisotopes and Reperfusion-Injury

The study aims to characterize age-associated changes in skeletal muscle bioenergetics by evaluating the response to ischemia-reperfusion in the skeletal muscle of the Goto-Kakizaki (GK) rats, a rat model of non-obese type 2 diabetes (T2D). (31)P magnetic resonance spectroscopy (MRS) and blood oxygen level-dependent (BOLD) MRI was performed on the hindlimb of young (12 weeks) and adult (20 weeks) GK and Wistar (control) rats. (31)P-MRS and BOLD-MRI data were acquired continuously during an ischemia and reperfusion protocol to quantify changes in phosphate metabolites and muscle oxygenation. The time constant of phosphocreatine recovery, an index of mitochondrial oxidative capacity, was not statistically different between GK rats (60.8 ± 13.9 sec in young group, 83.7 ± 13.0 sec in adult group) and their age-matched controls (62.4 ± 11.6 sec in young group, 77.5 ± 7.1 sec in adult group). During ischemia, baseline-normalized BOLD-MRI signal was significantly lower in GK rats than in their age-matched controls. These results suggest that insulin resistance leads to alterations in tissue metabolism without impaired mitochondrial oxidative capacity in GK rats.

Topics: Animals; Brain Ischemia; Diabetes Mellitus, Type 2; Disease Models, Animal; Hydrogen-Ion Concentration; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Male; Mitochondria; Muscle, Skeletal; Phosphocreatine; Phosphorus Radioisotopes; Rats; Reperfusion Injury

The effects of prostaglandin E1 (PGE1) and tyrosine kinase inhibitors on hepatic energy status and protein synthesis in ischemic livers were studied using 31P-magnetic resonance spectroscopy in a rat model. The continuous administration of PGE1 significantly increased the beta-adenosine triphosphate/inorganic phosphate (beta-ATP/Pi) ratio and hepatic protein synthesis rate (HPS) after ischemia-reperfusion injury. Microscopic examination showed that the continuous administration of PGE1 inhibited the development of sinusoidal hemorrhage and edema. Thus, it was concluded that PGE1 has a beneficial effect on ischemia-reperfusion injury in the liver. Pretreatment with tyrosine kinase inhibitor also increased the beta-ATP/Pi ratio; however, when tyrosine kinase inhibitor was injected before ischemia, the HPS became significantly reduced. Based on these data, the protective effect of tyrosine kinase inhibitor is unconvincing.

Topics: Alprostadil; Animals; Energy Metabolism; Ischemia; Liver; Magnetic Resonance Spectroscopy; Male; Phosphorus Radioisotopes; Protein Synthesis Inhibitors; Protein-Tyrosine Kinases; Rats; Rats, Wistar; Reperfusion Injury

Catecholamines can overcome myocardial stunning. However, a previous report on energy metabolism in stunned myocardium during catecholamine infusion was based on the conventional biochemical methods which might affect contractile function. Twenty farm pigs were anesthetized and underwent 15 min coronary artery occlusion and 2 h reperfusion. Ten pigs were given 10 micrograms/kg/min dobutamine from immediately after and throughout the reperfusion (dobutamine group). The other ten pigs were given saline (control group). Phosphorus-31 magnetic resonance spectroscopy and sonomicrometry were done alternately. Dobutamine improved percent segment shortening after reperfusion (control/dobutamine = 3.8%-5.7%/11.7%-13.4%; P < 0.01). At 15 min ischemia, adenosine triphosphate (ATP) decreased (control/dobutamine = 72 +/- 8%/73 +/- 10%, n.s.), and remained depressed after reperfusion in both groups. After reperfusion, phosphocreatine (PCr) returned to and maintained the preischemic value in the dobutamine group, while in the control group, PCr overshoot (112 +/- 5%) was observed. Except for the presence and absence of PCr overshoot, there was no significant difference of ATP and PCr between the two groups, although rate pressure product was significantly higher in the dobutamine group than in the control group. Regional myocardial blood flow after reperfusion was significantly higher in the dobutamine group. Dobutamine may improve "stunning" through effective improvement of energy utilization and production, indicated by the disappearance of PCr overshoot and maintained ATP level.

Topics: Adenosine Triphosphate; Animals; Blood Pressure; Catecholamines; Dobutamine; Energy Metabolism; Heart; Hemodynamics; Magnetic Resonance Spectroscopy; Microscopy, Electron; Myocardial Stunning; Myocardium; Phosphocreatine; Phosphorus Radioisotopes; Regional Blood Flow; Reperfusion Injury; Swine