Blood-to-Cerebrospinal Fluid Barrier For Cyclic Adenosine Monophosphate
in Man
Benjamin Rix Brooks, MD; W. King Engel, MD; Jonas Sode, MD the enzymes for their
\s=b\ A definite blood to lumbar CSF barrier for cyclic adenosine monophosphate (cAMP) exists in man under physiologic conditions. Lumbar CSF cAMP level remained unchanged, while the CSF glucose level rose significantly after a glucagon hydrochloride infusion that caused a 40-fold increase in the plasma cAMP level. (Arch Neurol 34:468-469, 1977)
degradation,7-"
concentration), cooled to 0 C, and centri¬ fugea immediately. The CSF samples (12 to 15) were divided into 1-ml aliquots, frozen immediately in dry ice, and stored for two to three weeks prior to assay. Plasma samples that had been similarly frozen were thawed prior to assay, and ultrafiltrates were prepared with an ultracentrifuge cone. Ultrafiltrates were as¬ sayed immediately or refrozen for assay on the subsequent day at dilutions beginning at 1:10. The CSF was thawed just prior to assay. Samples (1 ml) of CSF for cGMP assay were concentrated by evaporation
and
clic nucleotides in the CSF would provide information concerning cer¬ tain intracellular events in CNS tissues only in the presence of an effective blood-to-CSF barrier for these cyclic nucleotides.'"" To deter¬ mine whether such a barrier is present in man, we have measured CSF cAMP in 14 patients after significantly elevating the endogenous plasma cAMP level by means of glucagon hydrochloride infusion.12
Cyclic migraine,
nucleotides are measurable in human CSF.1-3 Ischemie dam¬ and seizures result in a age, significant rise in the CSF cyclic adenosine monophosphate (cAMP) concentration.46 The observed in¬ crease may reflect alterations of CNS tissues or merely the acute rise in plasma cAMP level that also occurs in patients with these disorders. Because mammalian CNS tissues contain large amounts of cAMP and cyclic guanosine monophosphate (cGMP) as well as
for one to two hours and taken up in 0.5 ml of 0.05M sodium acetate buffer at pH 6.2 just prior to assay. Samples of CSF for cAMP were diluted directly into the buffer at a final dilution of 1:5 prior to assay in duplicate. Cyclic adenosine monophosphate and cGMP levels were measured by radioimmunoassay." Standard samples prepared in artificial CSF (Elliott's solu¬ tion) were identical to those prepared in assay buffer (Schwarz-Mann). The glucose level was measured by the glucose oxidase method.13
PATIENTS AND METHODS
amyotrophic lateral sclero¬ neuropathies,' morphologically nonspecific myopathy," and vacuolar myopathy1 gave informed consent after the nature of the procedures had been fully explained to them. They remained at complete bed rest after an overnight fast prior to intravenous infusion of 0.45% saline, containing 20 mEq/liter KC1 at 75 ml/hr. Lumbar punctures were performed in the lateral decubitus position with a 20gauge needle that remained in position for Patients with
sis,7
Accepted
for publication April 1, 1977. From the Medical Neurology Branch, National Institute of Neurological and Communicative Disorders and Stroke (Drs Brooks and Engel), and the Endocrinology Branch, Medical Service, National Naval Medical Center (Dr Sode), Bethesda, Md. Reprint requests to the National Institutes of Health, Bldg 10, Room 10D18, Bethesda, MD 20014 (Dr Engel).
Plasma and
synthesis
measurements of cy¬
motor
RESULTS Intravenous infusion of glucagon for 30 minutes produced a 40-fold (mean) rise in the plasma cAMP concentration, maximal at conclusion of the infusion, that then declined exponentially over the ensuing 120
180 minutes." Simultaneous blood and CSF were obtained immediately prior to and after the start of an infusion of glucagon hydrochloride at 100 ng/kg/min for 30 minutes. Blood samples (10 ml) were collected in edetic acid (18 mg/ml final
samples
Cerebrospinal Fluid Metabolite Levels Time After Start of Intravenous
After
Glucagon
Glucagon Infusion,
min
Infusion
(Mean
±
SEM)
Metabolite Levels
(
14) cyclic adenosine monophosphate, pmole/ml Plasma cyclic guanosine monophosphate, pmole/ml Cerebrospinal fluid cyclic adenosine monophos¬ phate, pmole/ml Cerebrospinal fluid cyclic guanosine monophos¬ phate, pmole/ml Plasma glucose, mg/100 =
-30
-15
30
60
90
120
150
Plasma
Cerebrospinal fluid glu¬ cose, mg/100 ml
9.1
±
0.9
9.3 ± 0.9
9.8
0.9
427.0
158.0
±
28.0*
5.6
±
0.7
5.3
±
0.7
4.7 ± 0.4
6.7
0.7
6.5
±
0.8
6.3
±
5.5
±
0.8
7.2
±
1.1
6.6
±
1.1
6.5
1.2
6.6
1.1
6.2
±
1.6
±
0.1
1.4 ± 0.2
1.6
±
0.2
1.7
0.1
1.6
0.1
87.0
±
2.0
87.0
±
1.0
87.0
±
1.0
146.0
60.0
±
1.0
58.0
±
2.0
58.0
±
1.0
58.0
±
±
65.0s
5.0* ±
2.0
123.0 ± 62.0
"P at least less than .05, paired two-tailed f test.
Downloaded From: http://archneur.jamanetwork.com/ by a University of Michigan User on 06/18/2015
71.0 ±14.0*
27.0
6.0*
42.0
±
7.0*
0.6
7.1
±
0.5
6.7 ± 0.0
1.1
6.6 ± 1.2
6.2 ± 1.0
1.7
0.2
1.9
±
0.3
1.8 ± 0.0
6.0*
87.0
6.0
76.0
±
5.0*
77.0
±
3.0*
1.0
65.0
1.0
66.0 ± 1.0*
65.0
+
1.0*
±
500
-
to reflect specific changes in CNS concentrations of this nucleotide.1"" Therefore, in humans with intact
500
-
in Man
Benjamin Rix Brooks, MD; W. King Engel, MD; Jonas Sode, MD the enzymes for their
\s=b\ A definite blood to lumbar CSF barrier for cyclic adenosine monophosphate (cAMP) exists in man under physiologic conditions. Lumbar CSF cAMP level remained unchanged, while the CSF glucose level rose significantly after a glucagon hydrochloride infusion that caused a 40-fold increase in the plasma cAMP level. (Arch Neurol 34:468-469, 1977)
degradation,7-"
concentration), cooled to 0 C, and centri¬ fugea immediately. The CSF samples (12 to 15) were divided into 1-ml aliquots, frozen immediately in dry ice, and stored for two to three weeks prior to assay. Plasma samples that had been similarly frozen were thawed prior to assay, and ultrafiltrates were prepared with an ultracentrifuge cone. Ultrafiltrates were as¬ sayed immediately or refrozen for assay on the subsequent day at dilutions beginning at 1:10. The CSF was thawed just prior to assay. Samples (1 ml) of CSF for cGMP assay were concentrated by evaporation
and
clic nucleotides in the CSF would provide information concerning cer¬ tain intracellular events in CNS tissues only in the presence of an effective blood-to-CSF barrier for these cyclic nucleotides.'"" To deter¬ mine whether such a barrier is present in man, we have measured CSF cAMP in 14 patients after significantly elevating the endogenous plasma cAMP level by means of glucagon hydrochloride infusion.12
Cyclic migraine,
nucleotides are measurable in human CSF.1-3 Ischemie dam¬ and seizures result in a age, significant rise in the CSF cyclic adenosine monophosphate (cAMP) concentration.46 The observed in¬ crease may reflect alterations of CNS tissues or merely the acute rise in plasma cAMP level that also occurs in patients with these disorders. Because mammalian CNS tissues contain large amounts of cAMP and cyclic guanosine monophosphate (cGMP) as well as
for one to two hours and taken up in 0.5 ml of 0.05M sodium acetate buffer at pH 6.2 just prior to assay. Samples of CSF for cAMP were diluted directly into the buffer at a final dilution of 1:5 prior to assay in duplicate. Cyclic adenosine monophosphate and cGMP levels were measured by radioimmunoassay." Standard samples prepared in artificial CSF (Elliott's solu¬ tion) were identical to those prepared in assay buffer (Schwarz-Mann). The glucose level was measured by the glucose oxidase method.13
PATIENTS AND METHODS
amyotrophic lateral sclero¬ neuropathies,' morphologically nonspecific myopathy," and vacuolar myopathy1 gave informed consent after the nature of the procedures had been fully explained to them. They remained at complete bed rest after an overnight fast prior to intravenous infusion of 0.45% saline, containing 20 mEq/liter KC1 at 75 ml/hr. Lumbar punctures were performed in the lateral decubitus position with a 20gauge needle that remained in position for Patients with
sis,7
Accepted
for publication April 1, 1977. From the Medical Neurology Branch, National Institute of Neurological and Communicative Disorders and Stroke (Drs Brooks and Engel), and the Endocrinology Branch, Medical Service, National Naval Medical Center (Dr Sode), Bethesda, Md. Reprint requests to the National Institutes of Health, Bldg 10, Room 10D18, Bethesda, MD 20014 (Dr Engel).
Plasma and
synthesis
measurements of cy¬
motor
RESULTS Intravenous infusion of glucagon for 30 minutes produced a 40-fold (mean) rise in the plasma cAMP concentration, maximal at conclusion of the infusion, that then declined exponentially over the ensuing 120
180 minutes." Simultaneous blood and CSF were obtained immediately prior to and after the start of an infusion of glucagon hydrochloride at 100 ng/kg/min for 30 minutes. Blood samples (10 ml) were collected in edetic acid (18 mg/ml final
samples
Cerebrospinal Fluid Metabolite Levels Time After Start of Intravenous
After
Glucagon
Glucagon Infusion,
min
Infusion
(Mean
±
SEM)
Metabolite Levels
(
14) cyclic adenosine monophosphate, pmole/ml Plasma cyclic guanosine monophosphate, pmole/ml Cerebrospinal fluid cyclic adenosine monophos¬ phate, pmole/ml Cerebrospinal fluid cyclic guanosine monophos¬ phate, pmole/ml Plasma glucose, mg/100 =
-30
-15
30
60
90
120
150
Plasma
Cerebrospinal fluid glu¬ cose, mg/100 ml
9.1
±
0.9
9.3 ± 0.9
9.8
0.9
427.0
158.0
±
28.0*
5.6
±
0.7
5.3
±
0.7
4.7 ± 0.4
6.7
0.7
6.5
±
0.8
6.3
±
5.5
±
0.8
7.2
±
1.1
6.6
±
1.1
6.5
1.2
6.6
1.1
6.2
±
1.6
±
0.1
1.4 ± 0.2
1.6
±
0.2
1.7
0.1
1.6
0.1
87.0
±
2.0
87.0
±
1.0
87.0
±
1.0
146.0
60.0
±
1.0
58.0
±
2.0
58.0
±
1.0
58.0
±
±
65.0s
5.0* ±
2.0
123.0 ± 62.0
"P at least less than .05, paired two-tailed f test.
Downloaded From: http://archneur.jamanetwork.com/ by a University of Michigan User on 06/18/2015
71.0 ±14.0*
27.0
6.0*
42.0
±
7.0*
0.6
7.1
±
0.5
6.7 ± 0.0
1.1
6.6 ± 1.2
6.2 ± 1.0
1.7
0.2
1.9
±
0.3
1.8 ± 0.0
6.0*
87.0
6.0
76.0
±
5.0*
77.0
±
3.0*
1.0
65.0
1.0
66.0 ± 1.0*
65.0
+
1.0*
±
500
-
to reflect specific changes in CNS concentrations of this nucleotide.1"" Therefore, in humans with intact
500
-
