title: Concurrent measurements of cerebral blood flow, sodium, lactate, and high-energy phosphate metabolism using 19F, 23Na, 1H, and 31P nuclear magnetic resonance spectroscopy.
abstract: A new NMR technique for nondestructive, noninvasive, nonradioactive concurrent measurements of blood flow and several energy-dependent metabolites were applied to in situ cat brain during high cerebral blood flow states (seizures) and low flow states (carotid occlusion plus hemorrhagic shock). An inductively coupled, quadruple-tuned surface coil with a 50-ohm match at all relevant frequencies was used for both excitation and receiving. A broadband spectometer was used to measure the 31P spectrum (PCr, ATP, Pi, and pH), a water-suppressed 1H spectrum (lactate), 23Na, and 19F (blood flow via CHF3 washout). Each nucleus was excited at an independently determined rate. Sodium, with a short T1, was excited more frequently than phosphorus. The results qualitatively agreed with other techniques. Blood flow greatly increased during seizures with a 10% decrease in the Na signal, minimal lactate accumulation, no pH shift, and a change in the PCr-to-Pi ratio from 3.4 to 1.7. During carotid occlusion plus hypotension blood flow, PCr and ATP decreased to less than 10% of baseline values. Changes in PCr and Pi preceded parallel changes in Na and ATP. These experiments demonstrated the feasibility of concurrent measurements of physiologically induced changes in high-energy phosphates, lactate, sodium, and blood flow from the same volume of brain, in a nondestructive manner using NMR spectroscopy.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland.
authors.forename: S M
authors.initials: SM
authors.lastname: Eleff
authors.forename: M D
authors.initials: MD
authors.lastname: Schnall
authors.forename: L
authors.initials: L
authors.lastname: Ligetti
authors.forename: M
authors.initials: M
authors.lastname: Osbakken
authors.forename: V H
authors.initials: VH
authors.lastname: Subramanian
authors.forename: B
authors.initials: B
authors.lastname: Chance
authors.forename: J S
authors.initials: JS
authors.lastname: Leigh
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002415:Cats; D002560:Cerebrovascular Circulation; D005260:Female; D007773:Lactates / Q000378:metabolism*; D019344:Lactic Acid; D009682:Magnetic Resonance Spectroscopy; D010710:Phosphates / Q000378:metabolism*; D010725:Phosphocreatine / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*
chemical_list: D007773:Lactates; D010710:Phosphates; D010725:Phosphocreatine; D019344:Lactic Acid; D000255:Adenosine Triphosphate; D012964:Sodium