Cerebral blood flow and edema following carotid occlusion in the gerbil.

110

Summary:We have used the noninvasive method of "'phosphorus nuclear magnetic resonance C'P N MR) in \'il'O to follow changes in phosphorous me tabolite concentrations and the intracellular pH in the right and left hemi spheres and in the cerebellum of gerbil brains after the occlusion of the right carotid artery, Spatial resolution over the brain was possible using surface coils. Ligation, which is known to cause ischaemia in this species in the ipsilat eral hemisphere, resulted in the diminution of phosphocreatine and adenine nucleotides and a decrease in tissue pH. Less acidification occurred in the contralateral hemisphere and in the cerebellum. The high-energy metabolite concentrations, phosphocreatine and adenosine triphosphate (ATP), declined in unison in the ischaemic region, in marked contrast to the sequence of events in skeletal muscle, in which phosphocreatine buffers against an immediate fall in ATP concentration. In a separate series of gerbils, 31p NMR spectra were followed for exactly 1 h after carotid ligation. The animals were then sacrificed and brain grey matter specific gravity was rapidly measured to assess the development of oedema. There was a clear correlation between abnormality of spectra and the presence of oedema. It cannot, however, be confidently as serted that a normal spectrum is never seen in oedematous gerbil brains. 3' P NMR spectra specific gravity and histological changes shown by light micros copy have been correlated and show that useful signals are received from a depth of at least 4 mm or more from the lO-mm diameter coil.

Section: Resultsmentioning

confidence: 58%

Section: Methodsmentioning

confidence: 99%

A³¹P Nuclear Magnetic Resonancein vivoStudy of Cerebral Ischaemia in the Gerbil

Thulborn

Boulay

Duchen

et al. 1982

110

“…There were no significant differences between MK-801 -and placebo-treated groups (0 = normal, 1 2 = most severe damage). The most striking factor these studies have in common, besides the obvious decreases in neuronal damage, is that all employed some form of focal or forebrain ischemia (i.e., incomplete cerebral isch- (Levy and Brierley, 1974;Osburne and Halsey, 1975;Crockard et al, 1980;Suzuki et al, 1983). In the rat model of forebrain ischemia, as employed by Church et al (1988) and Park et al (1988a), Kagstrom et al (1983) shown to decrease to 25% of preischemic values within 4 min (Michenfelder and Theye, 1970).…”

Section: Figmentioning

confidence: 99%

MK-801, an Excitatory Amino Acid Antagonist, Does Not Improve Neurologic Outcome following Cardiac Arrest in Cats

Fleischer

Tateishi

Drummond

et al. 1989

Summary:The excitatory amino antagonist MK-80 1 was administered to cats following resuscitation from cardiac arrest to evaluate its effect on neurologic and neuropatho logic outcome in a clinically relevant model of complete cerebral ischemia. In 29 cats studied, cardiac arrest (ven tricular fibrillation) was maintained for 18 min and resus citation was successfully performed in 21 cats. Four an imals underwent a sham arrest. MK-80 1 or placebo was administered in a blinded, randomized manner. Beginning at 5 min post resuscitation (PR), MK-80 1 330 lLg/kg over 2 min fo llowed by 73 lLg/kg/h for 10 h or the same volume of placebo was administered. Resuscitated animals re mained paralyzed and sedated in an intensive care setting for 24--30 h PRo Neurologic examinations were performed at 2, 4, and 7 days PR by observers blinded to the treat ment groups. Seventeen cats were entered into data anal ysis (nine MK-80 1-treated and eight placebo-treated).There is considerable evidence suggesting that glutamate serves as a major excitatory neurotrans mitter in the mammalian central nervous system (Robinson and Coyle, 1987). There are at least three glutamate receptor subtypes, all of which probably act on the same ion channel complex to produce

“…Using the gerbil, which has an incomplete circle of Willis, it is possible to produce unilateral ischaemia of varying severity, with little or no change in the contralateral hemisphere (Crockard et al, 1980). Bilateral carotid occlusion produces profound homogeneous hemispheric cortical isch-aemia (Avery et aI., 1984).…”

mentioning

confidence: 99%

Acute Cerebral Ischaemia: Concurrent Changes in Cerebral Blood Flow, Energy Metabolites, pH, and Lactate Measured with Hydrogen Clearance and³¹P and¹H Nuclear Magnetic Resonance Spectroscopy. II. Changes during Ischaemia

Crockard¹,

Gadian²,

Frackowiak

et al. 1987

134

Summary: CBF has been measured with the hydrogen clearance technique in the two cerebral hemispheres of the gerbil under halothane anaesthesia. This has been correlated with changes in local pH, tissue lactate, and phosphorus energy metabolites measured in the same an imals with lH and 31p nuclear magnetic resonance spec troscopy. We demonstrate a threshold flow value for the The metabolic changes that are associated with reduced CBF have been extensively studied by many workers (Siesj6, 1978). When the flow falls sufficiently, there is a decline in high-energy phos phates, an increase in inorganic phosphate (P), an increase in lactate, and a decline in pH, and the time courses of these changes in acute ischaemia have been well documented in a number of animal models. However, much remains to be learned about the precise relationship between flow, energy consumption, and metabolic state. For example, can we define a critical threshold value of flow at which the energy status of the brain tissue becomes impaired, and how does this relate to thresholds for brain function? The results of Eklof and Siesj6Received December 11,1986; accepted February 20,1987 394 metabolic changes associated with energy failure at a level similar to the values previously reported for elec trical failure and tissue water accumulation, but higher than that associated with breakdown of extracellular po tassium homeostasis.