Interstitial Fluid Adenosine and Sagittal Sinus Blood Flow during Bicuculline-Seizures in Newborn Piglets

Park, T. S.; Wylen, D. G. L. Van; Rubio, Rafael; Berne, Robert M.

doi:10.1038/jcbfm.1987.116

Cited by 39 publications

(14 citation statements)

References 26 publications

(33 reference statements)

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“…Again, the precise mechanism is unknown, but previous studies have strongly implicated adenosine in mediating seizure arrest and postictal refractoriness (During and Spencer, 1992). Adenosine is known to be released during seizures in the newborn piglet (Park et al, 1987), but more studies are required to dissect the roles of adenosine and other inhibitory neuromodulators in the immature brain.…”

Section: Discussionmentioning

confidence: 99%

“…Consistent with this, the vehicle-treated asphyxia fetus that developed seizures showed a similar relationship between duration of events and the onset of tissue oxygenation. Finally, it is important to recognize that the precise relationship between duration of seizures and the timing of deoxygenation is very likely to be affected by factors such as the stage of maturation of the brain, the cause and nature of the seizures (e.g., idiopathic versus hypoxia-ischemia), the presence of pyrexia, or induced hypothermia, and potentially by species (Park et al, 1987). This may underlie the variable results found with nearinfrared spectroscopy studies of brain oxygenation in older children and adults.…”

Section: Discussionmentioning

confidence: 99%

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Cerebral Oxygenation during Postasphyxial Seizures in Near-Term Fetal Sheep

González

Hunter

Bennet

et al. 2005

J Cereb Blood Flow Metab

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After exposure to asphyxia, infants may develop both prolonged, clinically evident seizures and shorter, clinically silent seizures; however, their effect on cerebral tissue oxygenation is unclear. We therefore examined the hypothesis that the increase in oxygen delivery during postasphyxial seizures might be insufficient to meet the needs of increased metabolism, thus causing a fall in tissue oxygenation, in unanesthetized near-term fetal sheep in utero (gestational age 12571 days). Fetuses were administered an infusion of the specific adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine, followed by 10 mins of asphyxia induced by complete umbilical cord occlusion. The fetuses then recovered for 3 days. Sixty-one episodes of electrophysiologically defined seizures were identified in five fetuses. Tissue PO 2 (tPO 2 ) did not change significantly during short seizures (o3.5 mins), 5.270.2 versus baseline 5.670.1 mm Hg (NS), but fell to 2.270.2 mm Hg during seizures lasting more than 3.5 mins (Po0.001). During prolonged seizures, cortical blood flow did not begin to increase until tPO 2 had begun to fall, and then rose more slowly than the increase in metabolism, with a widening of the brain to blood temperature gradient. In conclusion, in the immature brain, during prolonged, but not short seizures, there is a transient mismatch between cerebral blood flow and metabolism leading to significant cerebral deoxygenation.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Cerebral Oxygenation during Postasphyxial Seizures in Near-Term Fetal Sheep

González

Hunter

Bennet

et al. 2005

J Cereb Blood Flow Metab

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“…CBF has been reported to increase dramatically during seizures due to a number of factors, such as hypercapnia, hypoxemia, respiratory and metabolic acidosis (3), arterial hypertension (4-7), and neurogenic (8) and myogenic activities (I 2). Also, seizures increase cerebral metabolism, which leads to an increase in dilating mediators including K+ (13), H+ (14), lactate (15,16). adenosine (1 5, 16), and prostanoids (1 7); these local mediators increase CBF.…”

Section: Discussionmentioning

confidence: 99%

Effects of Pancuronium Bromide on Cerebral Blood Flow Changes during Seizures in Newborn Pigs

et al. 1992

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ABSTRACT. We investigated the effects of pancuronium bromide pretreatment on cerebral blood flow (CBF) during bicuculline-induced seizures in anesthetized piglets. Arterial blood pressure, gases, pH, cerebral electrocortical activity, and CBF (radioactive microsphere) were monitored at baseline, 10 min after administration of pancuronium (0.3 mg/kg i.v.; n = 9) or vehicle (normal saline; n = 8), and again at 5, 15, and 60 rnin after bicuculline (3 mg/ kg i.v.). No change in CBF from baseline was observed at 10 rnin after either saline or pancuronium treatment, before induction of seizures. In the saline group, CBF was 36 f 3 mL. min-' . 100 g-' before bicuculline and increased to 166 k 24 and 205 f 35 mL,min-'.lo0 g-' at 5 and 15 min, respectively, after bicuculline, returning toward baseline by 60 min. In the pancuronium group at 5 min after bicuculline, CBF increased from 45 f 7 to 169 k 26 mL. m i d . 100 g-I, but fell to 88 f 17 mL. min-' . 100 g-' at 15 rnin in contrast to saline-treated piglets. Also, at 15 rnin of seizures, differences between groups were observed in arterial blood pressure, gases, and pH. Although these variables were in the normal range with pancuronium treatment, the saline-treated animals had increased arterial blood pressure (81 k 6 mm Hg) and Pco2 (6 5 0.4 kPa) and decreased Poz (7 2 0.5 kPa) and pH (6.91 f 0.06).Electrocortical activity was abnormal during seizures in both groups. At 60 min, reversal to normal activity was observed in six of nine pancuronium-treated animals versus two of eight saline-treated animals. These data suggest that pancuronium limits cerebral hyperemia during prolonged seizures by attenuating increases in blood pressure as a result of elimination of skeletal muscle activity. This leads to minimal alteration of arterial Pcoz, Poz, and pH during seizures. Supported in part by grants-in-aid from the American Heart AssociationTennessee Afliliate, the National Institutes of Health, and Obstetncs and Gynecology Special Education Fund. 6 dramatic increases in CBF (1). Factors contributing to augmented CBF are increased cerebral metabolic rate (2), metabolic and/or respiratory acidosis (3), and arterial hypertension (4-7). This rise in CBF is also exaggerated by neurogenic mechanisms (8). Babies prone to seizures often have respiratory problems and are given muscle relaxants to ease mechanical ventilation and oxygenation. However, inasmuch as pancuronium therapy has been reported to impair cerebrovascular autoregulation in neonatal animals (9), it is unclear whether such therapy would be beneficial.The purpose of this study was to examine the effects of pancuronium on seizure-induced cerebral hyperemia in newborn pigs. We tested the hypothesis that pancuronium would limit perturbations of arterial blood gases, pH, and blood pressure produced by skeletal muscle activity during prolonged seizures and consequently would limit increases in CBF during seizures. MATERIALS AND METHODSThe animal protocol was reviewed and approved by the Animal Care and Use Committee of Th...

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“…The blood flow signal from the ICBF probe was calibrated volumetrically against SS emuent using a modification of the methodology of Park et al (17,18) and Traystman and Rapela (20). We attempted to ensure that NNLA or INDO administration did not affect the ICBF signal (by, for example, redirecting ICBF to extracranial sites) in the following manner.…”

Section: Materials a N D Methodsmentioning

confidence: 99%

“…An SS catheter was placed by following the methodology of Park et al ( 17,18). A 2-cm diameter cranial burr hole was made in the midline halfway between the nasion and inion, and the SS was identified.…”

Section: Materials a N D Methodsmentioning

confidence: 99%

The Role of Prostaglandins and Endothehum-Derived Relaxation Factor in the Regulation of Cerebral Blood Flow and Cerebral Oxygen Utilization in the Piglet: Operationalizing the Concept of an Essential Circulation

et al. 1994

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ABSTRACT. The brain is considered an "essential" organ, defined as one whose blood supply is preferentially maintained vis-a-vis other less-essential circulations during periods of reduced systemic cardiac output (CO). We asked whether the actions of either prostaglandins or endothelium-derived relaxation factor might underlie the essential qualities of the cerebral circulation; that is, would the absence of one or the other impair the ability of the brain to preferentially redirect systemic blood flow during a period of reduced systemic CO. We compared hemodynamics in the cerebral and systemic circulations in 33 anesthetized piglets under three conditions that reduced systemic CO equivalently: endothelium-derived relaxation factor inhibition with the substituted L-arginine analog Nnitro-L-arginine (NNLA; 25 mg/kg), prostaglandin inhibition with indomethacin (INDO, 5 mglkg), and inflation of a left atrial balloon (LAB) catheter. NNLA, INDO, and LAB each reduced CO to an equivalent value (-30% from baseline). NNLA and INDO, but not LAB elevated systemic blood pressure, cerebral perfusion pressure (CPP), systemic vascular resistance (SVR), and cerebral vascular resistance (CVR). Cerebral blood flow (CBF) was preserved after NNLA and LAB but fell after INDO (-35%).Despite the equivalent reduction in CO noted during the three experimental protocols, the proportion of systemic blood flow directed toward the brain (CBFICO) rose significantly during LAB and NNLA (+30%) but fell significantly during INDO (-12%). Similarly, relative cerebral vascular resistance (CVRISVR) fell significantly during LAB and NNLA but rose during INDO. Cerebral vascular regulation can be considered along two complementary dimensions. Vascular regulation within the cerebral circulation itself (cerebral autoregulation) is expressed as CBF versus CPP. CBF was unchanged as CPP fell during LAB and as CPP rose after NNLA in piglets. In contrast, after INDO, CBF fell as CPP rose. Vascular regulation of the cerebral circulation vis-a-vis the rest of the body (referred to here as cerebral-specific vascular regulation) can be expressed either in terms of blood flow (CBFICO) or vascular resistance (CVRISVR). After both NNLA and LAB, as CO fell, CBFICO rose and CVRISVR fell, demonstrating preservation of the "essential" status of the cerebral circulation. In contrast, after INDO as systemic CO fell, CBFICO fell and CVRISVR rose. Prostaglandins,

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Interstitial Fluid Adenosine and Sagittal Sinus Blood Flow during Bicuculline-Seizures in Newborn Piglets

Cited by 39 publications

References 26 publications

Cerebral Oxygenation during Postasphyxial Seizures in Near-Term Fetal Sheep

Cerebral Oxygenation during Postasphyxial Seizures in Near-Term Fetal Sheep

Effects of Pancuronium Bromide on Cerebral Blood Flow Changes during Seizures in Newborn Pigs

The Role of Prostaglandins and Endothehum-Derived Relaxation Factor in the Regulation of Cerebral Blood Flow and Cerebral Oxygen Utilization in the Piglet: Operationalizing the Concept of an Essential Circulation

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