Analysis of equine cisterna magna cerebrospinal fluid for the presence of some monoamine neurotransmitters and transmitter metabolites.

Small volumes (0.05 ml) of cisterna magna cerebrospinal fluid (CSF) from 23 neurologically normal horses were analysed for the monoamine neurotransmitters dopamine, norepinephrine, epinephrine, serotonin and their metabolites using high pressure liquid chromatography and electrochemical detection. Two metabolites, homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) were present in all CSF samples. The deaminated and methylated metabolite of dopamine, HVA, was present at a mean concentration of 42.33 +/- 3.14 ng/ml of CSF. The deaminated metabolite of serotonin, 5-HIAA, was present at a mean concentration of 45.52 +/- 3.65 ng/ml of CSF. A positive correlation was found between the CSF concentrations of HVA and 5-HIAA (r = 0.72, p = 0.0003). The mean ratio of HVA to 5-HIAA concentrations was 1.07 +/- 0.05. The ratios of HVA to 5-HIAA concentrations were found to be more indicative of the serotonergic metabolite 5-HIAA (r = -0.62, p = 0.0016) than the dopaminergic metabolite HVA (r = 0.11, p = 0.60). There was a stronger relationship between the concentrations of 5-HIAA and the ratios of HVA to 5-HIAA in male CSF (r = -0.85, p = 0.0006) than in female CSF (r = -0.54, p = 0.01). Concentrations of CSF neurotransmitter metabolites were evaluated in horses grouped by age (0-4, 5-9 and 10-13 years). The youngest group of horses had a significantly (p = 0.003) greater CSF concentration of HVA than of 5-HIAA. The 10-13-year-old horses had a significantly (p = 0.02) lower mean CSF HVA concentration than the 0-4-year-old horses. No age-related differences in CSF 5-HIAA concentrations were detected.

Gradient of arginine vasopressin concentration but not angiotensin II concentration between cerebrospinal fluid of anterior 3rd ventricle and cisterna magna in dogs.

Dogs were chronically implanted with two devices for cerebrospinal fluid (CSF) sampling from (a) the anterior part of the 3rd ventricle and (b) the cisterna magna. In conscious dogs arginine vasopressin (AVP) concentration of CSF samples collected at different occasions were 2-3 times higher in the CSF of the 3rd ventricle as compared to the AVP concentration of the cisterna magna. Inhalation anesthesia stimulated AVP release into the CSF at both sites by a factor of about 2, the gradient between 3rd ventricle and cisterna magna CSF of 2-3 remained for AVP in simultaneously collected samples. In contrast, angiotensin II-like immunoreactivity of CSF was not significantly different at both sites, neither in the conscious dogs nor during anesthesia. It is concluded that the main amount of AVP enters the CSF at the 3rd ventricular level.

Increased brain interstitial fluid adenosine concentration during hypoxia in newborn piglet.

The effects of arterial hypoxia on interstitial fluid adenosine concentrations were studied in the frontal cortex and thalamus by the brain dialysis technique and in CSF from the cisterna magna of the newborn piglet. Acute hypoxia (PaO2 = 20 +/- 1 mm Hg) increased the interstitial fluid adenosine concentrations significantly from 0.68 +/- 0.29 (SEM) to 1.60 +/- 0.35 microM in the frontal cortex and from 1.03 +/- 0.32 to 2.60 +/- 0.86 microM in the thalamus (n = 8). Interstitial fluid inosine and hypoxanthine also increased significantly during hypoxia. In separate groups of piglets, the adenosine concentration in the cisterna magna CSF under normoxic conditions was 0.04 +/- 0.01 microM (n = 5), which increased significantly to 0.17 +/- 0.04 microM (n = 6) with hypoxia (PaO2 = 4.7 +/- 1.2 mm Hg). Cisterna magna CSF inosine levels did not change significantly during the severe hypoxia. Adenosine concentrations found in the interstitial space and CSF of newborn piglets under normoxic and hypoxic conditions are within the vasodilator range. These results thus suggest that in the neonatal brain adenosine may play a role in regulating blood flow during hypoxia.

Computed tomography number correlations for metrizamide computed tomographic ventriculography.

The authors describe a method that permits the determination of the precise intraventricular iodine concentration after metrizamide computed tomographic ventriculography. There is an observed linear relationship between computed tomography number (Hounsfield units) and iodine concentration. This relationship may be used to provide the basis for a method of evaluating ventricular fluid dynamics. This, in turn, is useful for the determination of the indications for a shunting procedure and for the evaluation of shunt function in a patient with an existing shunt.

Effect of probenecid on cerebral and cisternal cerebrospinal fluid lactate content.

In this study, the cisternal CSF contents of lactate and glucose were sequentially measured in free-moving rats that had been administered probenecid, 200 mg/kg-1, drug diluent, or no injections. In animals receiving either no injections or injections of drug diluent, CSF lactate and glucose were constant over a 6-h period (93-106% of control), whereas rats receiving probenecid showed increased lactate at 1 and 2 h (170 and 125% control, respectively) and increased glucose at 1, 2, and 3 h (169, 141 and 129% control, respectively). Cerebral cortex content of energy metabolites and lactate and blood lactate levels were statistically unaltered at 0.5-6 h exposure to probenecid, whereas cerebral and blood glucose contents were increased after 1 and 2 h exposure to probenecid. Rats exposed to 5% O2 and probenecid for 0.5 h showed a statistically higher CSF lactate at 0.5 and 1.5 h reoxygenation (169 and 168% control, respectively). A similar effect was also seen in rats exposed to 5% O2 and the 5-hydroxyindoleacetic acid (5-HIAA) transport inhibitor Na divalproate. The results suggested that the increase in CSF glucose was secondary to a probenecid-induced elevation of blood glucose, whereas the increase in CSF lactate seemed to be secondary to a reduced rate of efflux of lactate from the CSF. It is suggested that it may be possible to increase the CSF lactate content by mechanisms that are independent of direct effects on the processes of cerebral energy metabolism.

Brain damage in profound hypothermia. Perfusion versus circulatory arrest.

To investigate brain changes in induced deep core hypothermia (18 degrees C) with or without circulatory arrest, four groups of dogs were subjected to cardiopulmonary bypass (CPB) under the following conditions: (1) differential head perfusion with pulsatile flow and simultaneous circulatory arrest to the rest of the body; (2) differential perfusion to the head with a nonpulsatile flow; (3) total circulatory arrest; and (4) continuous hypothermic perfusion. Parameters analyzed were: (1) blood flow distribution; (2) creatine kinase isoenzyme (CK-BB) elevation in the cerebrospinal fluid (CSF) and in the brain venous return; and (3) microscopy of the brain in animals killed at 30 minutes, 24 and 48 hours, 1 and 2 weeks, and 1 month. Although minor brain tissue flow differences were found at 37 degrees C among the groups, flows equalized at 18 degrees C. A significant seven-fold brain flow increase followed the period of circulatory arrest in Group III. Rise of CK-BB levels occurred in brain venous return but not in CSF in all groups. Microscopic cellular damage appeared in all groups with an equal degree of severity, regardless of the method of hypothermia and perfusion implemented.

New method for the collection of cerebrospinal fluid from the cisterna magna of conscious dogs.

We have developed a catheter system than can be implanted chronically into the cisterna magna of the dog to obtain serial samples of cerebrospinal fluid (CSF) for up to 8 wk. A direct access to the CSF of the cisterna magna provided an opportunity to determine also base-line values of CSF sodium, potassium, norepinephrine, epinephrine, and angiotensin II immunoreactivity and compare relative differences in the concentration of these variables between the central and peripheral compartments.

[Total proteins of the cerebrospinal fluid obtained by punction of the cisterna magna: normal values. Variations related to sex]. / Proteinas totais do liquido cefalorraqueano obtido por punção da cisterna magna: valores normais. Variações ligadas ao sexo

The total protein content of CSF collected from the cisterna magna (cisternal fluid) of 98 patients (58 males and 40 females) with no neurological diseases was determined by the colorimetric method devised by Lowry and co-workers. This method has been previously chosen based mainly on it's sensitivity, accuracy and low fluid consumption. The CSF samples were normal with regard to pressure, color, citology and it's content in glucose, chloride and urea. Complement fixation tests for syphilis and cisticercosis, as well as the globulin tests (Pandy, Nonne--Appelt and Takata-Ara) were negative. The average value and the normal range of cisternal fluid total protein was calculated for the mixed population (males and females). The mean protein value was 26.78 mg/100 ml, the lower and upper limits were respectively 13.20 and 40.36 mg/100 ml. These data are higher than those stated in some publications, and factors that could interfere in the different results mentioned in the literature are briefly discussed. Since the statistical analysis of the results showed that the mean total protein concentration in males (28.76 mg/100 ml) was higher than in females (23.91 mg/100 ml), normal limits for each sex were established: 16.96 to 47.13 mg/100 ml for males and 14.76 to 42.76 mg/100 ml for females.

Is brain prostaglandin synthesis involved in responses to cold?

1. Experiments with rats have suggested that prostaglandin synthesis in the C.N.S. may mediate thermoregulatory reactions to cold. This possibility was investigated in cats using two types of experiment. 2. In one series of experiments, c.s.f. collected from the cisterna magna of conscious cats exposed to a cold and a hot environment was assayed for prostaglandin-like activity. During cold exposure there was a slight increase in activity which persisted after return to neutral ambient temperature. There was no correlation between prostaglandin-like activity and rectal temperature. During the heat exposure there was no demonstrable change in activity. 3. In the second series, conscious cats were exposed to cold conditions and given intravenous injections of salicylate, paracetamol, or indomethacin, all of which inhibit prostaglandin synthesis. Indomethacin salicylate nor paracetamol caused any significant change in rectal temperature. 4. The results do not support a role for C.N.S. prostaglandin synthesis in thermoregulatory reactions to cold in cats.

3-Methoxy-4-hydroxy-phenylglycol sulfate (MOPEG-SO4) in ventricular and cisternal cerebrospinal fluid of dogs.

Cerebrospinal fluid was collected from the lateral ventricles and cisternal space from beagle dogs under light pentobarbital anesthesia. Homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA), and 3-methoxy-4-hydroxyphenylglyco-sulfate (MOPEG-SO4) levels in the liquor taken from these two regions were evaluated, and the ventricular-cisternal ratio (V/C) was calculated for each monoamine metabolite. A marked similarity in the V/C ratio of 6:1 for 5-HIAA and 5:1 for MOPEG-SO4, as compared to a much higher V/C ratio of 18:1 for HVA, perhaps reflects the more diffuse distribution of norepinephrine and serotonin, precursor amines, as compared to dopamine in the CNS and also emphasizes the probable existence of an active transport mechanism for the removal of MOPEG-SO4, as has been well documented for 5-HIAA and HVA.

Composition of fluid obtained from choroid plexus tissue isolated in a chamber in situ.

1. A method was developed for isolating a segment of the choroid plexus of the lateral ventricle of the cat brain in a chamber in situ.2. A comparison of electrolyte and protein concentrations in serum, ultrafiltrate of serum, cisterna magna fluid, fluid accumulated in the chamber and fluid collected from the choroid plexus by another technique, demonstrates that the chamber fluid is a secretory product of the choroid plexus.3. The rate of fluid formation in the chamber was 0.4 mul. min(-1) mg(-1) of tissue, a value in good agreement with reports in the literature.4. The observation that the concentration of K(+) in choroid plexus fluid was lower than that in the serum ultrafiltrate suggests that K(+) is regulated by an active transport process at the choroid plexus.5. Significant correlation was found between electrolyte values and the protein content of the chamber fluid. This suggests that plasma is the probable source of the protein in the chamber fluid and that K(+) and probably Ca(2+) and Mg(2+) in c.s.f. are subject to active homoeostatic regulation by the choroid plexus.6. The technique described provides a new opportunity to study in detail the functional characteristics of the choroid plexus.

The ontogenesis of haematoencephalic cation transport processes in the rhesus monkey.

1. This investigation was undertaken to determine the time course of development of cation transport processes between blood and the extracellular fluid compartments of the central nervous system (C.N.S.) of the foetal rhesus monkey. The development of concentration gradients within the cerebrospinal fluid (c.s.f.) system was also studied in an attempt to gain information on regional variations in transport activities.2. Cerebrospinal fluid samples were obtained from the lateral ventricle, the cisterna magna, the cortical subarachnoid space and the lumbar region of the spinal subarachnoid space of adult monkeys. Foetal c.s.f. samples were obtained from the cisterna magna and the frontal region of the cortical subarachnoid space. Blood samples were taken within 3-10 min of the c.s.f. samples. The concentration of K, Mg and Ca were determined on appropriately diluted samples by atomic absorption spectrophotometry.3. The concentrations of K, Mg, and Ca in the plasma and c.s.f.s of the adult monkey are similar to those of other mammalian species. The c.s.f./blood concentration gradients of these cations are in the same direction but generally of greater magnitude than those in non-primate mammals. The indicated [Mg] in the extracellular fluid of the adult monkey's cerebral cortex is high (more than 2 m-equiv/kg H(2)O) and the [K] is low (less than 2 m-equiv/kg H(2)O).4. Accumulation of Mg into the c.s.f. system against a concentration gradient is evident in the earliest foetuses studied (50 days of intrauterine life) and by the second half of gestation the concentration gradients of this cation are similar to that of the adult.5. In the second trimester foetus, the [K] in the cisternal fluid is near the plasma ultrafiltrate level. It then decreases gradually throughout the remainder of gestation, approximating the adult value at birth.6. The very low [K] typical of the adult cortical subarachnoid fluid is observed by the sixth month following birth but not during foetal life or within the first few weeks of post-natal life. This indicates that the transport processes at the cortical region of the haematoencephalic interphase do not fully develop until well after birth.7. It is concluded that the various transport processes responsible for the elaboration and maintenance of adult type of K, Ca and Mg concentrations within the extracellular fluid compartments of the monkey C.N.S. do not develop at the same time. This temporal dissociation provides strong evidence against any direct association or coupling between the haematoencephalic K and Mg transport systems.8. Existence of normal cation concentration gradients between c.s.f. and blood may serve as a criterion for the normality of the (foetal) blood-brain barrier.