phosphorus-radioisotopes and Intermittent-Claudication

1. We set out to define abnormalities of oxidative ATP synthesis, cellular proton efflux and the efficiency of ATP usage in gastrocnemius muscle of patients with claudication due to peripheral vascular disease, using data obtained by 31P magnetic resonance spectroscopy during aerobic exercise and recovery. 2. Eleven patients with moderate claudication were studied and results were compared with 25 age-matched control subjects. Changes in pH and phosphocreatine concentration during recovery were used to calculate the maximum rate of oxidative ATP synthesis (Qmax.) and the capacity of net proton efflux. Changes in pH and phosphocreatine concentration were used to estimate rates of non-oxidative and (indirectly) oxidative ATP synthesis throughout exercise, taking account of abnormalities in proton efflux during exercise. 3. In patients with claudication, slow post-exercise phosphocreatine recovery showed a 42 +/- 9% decrease in Qmax., and the slow ADP recovery was consistent with this. pH recovery was slow, showing a 77 +/- 9% decrease in the capacity for proton efflux. Both abnormalities are compatible with a substantial reduction in muscle blood flow. 4. During exercise, increased phosphocreatine depletion and intracellular acidification were a consequence of impaired oxidative ATP synthesis and the consequent increase in non-oxidative ATP synthesis, compounded by reduced proton efflux. The acidification prevented an increase in ADP concentration which could otherwise partially compensate for the oxidative defect. All these abnormalities are compatible with a reduced muscle blood flow. 5. In addition, initial-exercise changes in pH and phosphocreatine concentration implied a 44 +/- 5% reduction in 'effective muscle mass', necessitating an ATP turnover (per litre of muscle water) twice as high for given power output as in control muscle. Some of this is probably due to a localized loss of muscle fibres, but the rest appears to reflect reduced metabolic efficiency of the muscle. This is not a direct consequence of reduced blood flow, and may be related to change in muscle fibre type.

Topics: Adenosine Triphosphate; Adult; Aged; Aged, 80 and over; Case-Control Studies; Female; Glycogen; Humans; Intermittent Claudication; Magnetic Resonance Spectroscopy; Male; Middle Aged; Mitochondria, Muscle; Muscle, Skeletal; Peripheral Vascular Diseases; Phosphorus Radioisotopes

Using 31P nuclear magnetic resonance spectroscopy of the calf muscle, the authors studied patients with peripheral arterial occlusive disease. They studied PCr depletion and intracellular pH during aerobic exercise in patients and controls. The phosphocreatine (PCr) index ([PCr]/([PCr] + [Pi])) at rest was correlated with blood flow measured by plethysmography. During aerobic exercise a greater decrease in pH was obtained in patients (p < 0.03). They also studied the work necessary to reach a PCr index = 0.5 during ischemic exercise. This workload was lower in patients than in controls: 32.99 +/- 3.04 J vs 58.89 +/- 8.55 J, p < 0.05. After vasodilator therapy the workload was improved in patients: 32.99 +/- 3.04 J vs 38.85 +/- 3.54 J, p < 0.05. These results suggest that therapy resulted in improved tissue perfusion in patients.

Topics: Arterial Occlusive Diseases; Exercise; Humans; Hydrogen-Ion Concentration; Intermittent Claudication; Ischemia; Leg; Magnetic Resonance Spectroscopy; Middle Aged; Oxidative Phosphorylation; Phosphocreatine; Phosphorus Radioisotopes; Vasodilator Agents

Muscle metabolism was measured in 7 patients with arterial occlusive disease and symptoms of intermittent claudication both before and after percutaneous vascular neurolysis by means of dynamic 31P-MR spectroscopy. Phosphorus spectra of the involved calf muscles were determined before, during and after defined treadmill exercise. In addition to pH values the phosphocreatine content was measured during activity and recovery phases. There was close correlation in these patients between the increase in claudication distance and more rapid regeneration of phosphocreatine following neurolysis. However, none of the patients achieved normal values of phosphate metabolism. By means of the non-invasive 31P-MR spectroscopy it was possible for the first time to demonstrate the biochemical changes associated with neurolytic lumbar sympathetic blockade.

Topics: Adult; Aged; Aged, 80 and over; Arterial Occlusive Diseases; Energy Metabolism; Exercise Test; Female; Humans; Intermittent Claudication; Leg; Magnetic Resonance Spectroscopy; Male; Middle Aged; Muscles; Phosphorus Radioisotopes

31P in-vivo spectroscopy was performed by a 1.5-tesla whole-body MR system. The 31P spectrum for the calf muscle in a patient with arteriosclerosis obliterans having intermittent claudication was obtained every two minutes. When the spectrum after the workload was compared with that at rest, an increase in inorganic phosphate (Pi) and a decrease in phosphocreatine (PCr) were observed, resulting in a strong decrease in the PCr/Pi ratio. This method can measure the ischemic and recovery stages of energy metabolism in skeletal muscle noninvasively and continuously in addition to magnetic resonance imaging.

Topics: Aged; Angiography; Arteriosclerosis Obliterans; Energy Metabolism; Humans; Intermittent Claudication; Leg; Magnetic Resonance Spectroscopy; Male; Muscles; Phosphates; Phosphocreatine; Phosphorus Radioisotopes; Radionuclide Imaging