Acta neurol. scandinav. 57, 257-261, 1978
SHORT COMMUNICATION
Depts. of Clinical Neurology and Clinical Physiology, Karolinska Sjukhuset, Dept. of Anatomy, Karolinska Institutet, Stockholm, Sweden
Capillary permeability in ALS, determined through transcapillary escape rate of "sI-albumin
s. CONRADI, L. KAIJSERA N D L.-o. RONNEVI Since various macromolecules have experimentally been demonstrated to be taken u p by the motor end-plates and subsequently transported through retrograde axoplasmic flow, noxious substances may gain entrance to the lower motorneurons through the same route. Consequently, the function of the capillary barrier in skeletal muscle is of interest in diseases of the lower motorneurons. The transcapillary escape rate of 1251-albuminwas determined in six ALS patients. The values fell within the range earlier reported for normals. INTRODUCTION The retrograde axoplasmic flow of the lower motorneurons may have pathogenetic significance in diseases of the motomeurons. Certain macromolecules, such as albumin and horseradish peroxidase have been demonstrated t o be taken up by motor endplates and transported intraaxonally to the motorneuron cell bodies in spinal cord and brain stem (Kristensson 1970, Kristensson & Olsson 1971, Stockel et al. 1975). There is experimental evidence that substances capable of damaging the motorneurons can be transported through the same route (see Kristensson 1975, Ronnevi et al. 1973). This focuses the interest on the function of the capillary b a m e r in skeletal muscle as a protection of the end-plates and thereby the motorneurons against various potentially noxious substances in blood. The present study deals with the capillary permeability of albumin in amyotrophic lateral sclerosis (ALS), determined through the transcapillary escape rate of lZ5Ilabeled human serum albumin (TERald, according to Parving & Gyntelberg (1973). There are earlier reports on capillary abnormalities occurring in ALS, based on histological studies (Kniffer & Quick 1969, Stortebecker et at. 1970) and quantitative studies of CSF proteins (Kjellin & Stibler 1976). MATERIAL AND METHODS Six patients with ALS were studied. The diagnoses were settled by conventional clinical methods, and the patients showed either predominantly peripheral, bulbar or pyramidal symptoms. None of the patients had clinical signs of diabetes, malignancy or hypertension. The transcapillary escape rate was determined according to Parving & Gyntelberg by measuring '=I-activity in venous plasma samples without stasis before and at 15-min intervals during the first hour after intravenous administration of the substance. Mean dilution rate of the albumin was then calculated, assuming a mono-
Born
1922
1928
1932
1934
1922
1943
Sex
M
M
M
F
F
F
Name
W.B.
G.B.
S.R.
G.S.
S.J.
E.S.
1973
1974
1971
1972
1971
N
58
1972
47
52
40
57
61
Weight (kg)
OnSet
Year of
16.0
25
-
29.5
38.9
38.6
33.7
[Alb.]/CSF (mg/100 ml)
3.3
3.9
3.9
4.3
5.1
4.2
(1)
2.1
2.5
2.6
2.7
3.3
2.4
Plasma volume (1)
Table 1 . Details of the measurements on the individual patients
146
151
132
5.3
5.1
5.9
5.7
4.5
4.0
(%I
TER,,dl
Mean 5.1 Normal 5.6 f 1.1
43
43
40
43
44
152 145
48
(%I
Hematocrit
166
Hemoglobin
00
VI
h)
25 9 exponential escape. Blood and plasma volumes were estimated from the pre- and 15-min post-injection activity of whole blood and plasma samples separately. The values given for blood volume were corrected for the difference in venous and mean body hematocrit, assuming that the body hematocrit was 0.91 X the venous hematocrit. In order to obtain an additional measure of capillary function, [albumidCSF was also calculated through paper electrophoresis. Table 1 shows the various measurements.
RESULTS As seen in Table 1, the values for TER,,, in the ALS group are in the same order of size or lower than in normals. Since the extravasation of albumin is closely related to plasma volume (Walker et al. 1960), the correlation between these parameters was also studied (Fig. 1). Likewise, the vaIues from the ALS patients are found within the normal range. Half of the ALS cases showed slightly elevated [albumin]/CSF (> 30 mg/100 ml), but there seemed to be no correlation between these values and TERa,h'
DISCUSSION The iodated albumin can be considered t o behave like endogenous albumin (Parving & Gyntelberg 1973). Further, the disappearance of albumin from blood during the first hour after the infusion has been shown t o reflect - practically totally - the extravasation to interstitial fluid, rather than degradation and excretion (see also Wasserman & Mayerson 1951). The method does, however, not permit differentiation between extravasation of the albumin in muscle and in other tissues. Important factors determining the transcapillary escape rate of albumin in normals are plasma volume and body weight (Walker et al. 1960). Despite the fact that several of the patients had undergone a pronounced loss of weight during the course of the disease, it can be seen that the levels of plasma volumdkg body weight in the patient group did not deviate from normal to, any noticeabmle extent.
TER
alb.
( per cent
/ hour
)
10 1
Plasma volume ( ml / kg
)
Figure I . Relation between TER,,, and plasma volume in the individual ALS patients (circles). Regression lines are for normal subjects (striped) and patients with hypertension (solid), according to Parving & Gyntelberg (1973).
260 Thus, the overall transcapillary escape rate of albumin was found to be normal in the actual ALS patients, although the method previously has permitted the demonstration of an increased escape rate in patients with hypertension (Parving & Gyntelberg 1973). Since albumin is the dominating osmotic factor at the capillary level, it can furthermore be supposed that there ought to be no drastic abnormalities of the bulk flow of plasma across the capillary walls in ALS. There may, of course, be restricted capillary permeability changes, which cannot be demonstrated with the present method. Regarding potentially noxious substances in plasma in ALS, we are currently investigating the turnover and tissue distribution of lead, since there are several earlier reports on overexposure to lead in ALS (Currier & Haerer 1968, Campbell et al. 1970, Felrnus et al. 1976). Our primary interest is devoted to the question of availability of this metal to the motor end-plates (see Conradi et al. 1976, 1977). The binding of lead in plasma is not known in detail, although it has been claimed that the metal is bound t o bo'th small molecules, such as polypeptides, and larger ones, possibly albumin (Griffin & Matson 1972). Concerning lead in ALS, the present findings therefore seem to increase the interest for further studies on the mechanisms of binding 04 the metal to various plasma constituents.
ACKNOWLEDGMENT The studies were supported by Stiftelsen MS-Fonden. REFERENCES Campbell, A. M. G., E. R. Williams & D. Barltsop (1970): Motor neuron disease and exposure to lead. J. Neurol. Neurosurg. Psychiat. 33, 877-885. Conradi, S., L.-0. Ronnevi & 0.Vesterberg (1976): Abnormal tissue distribution of lead in amyotrophic lateral sclerosis. J. Neurol. Sci 29, 259-265. Conradi, S., L.-0. Ronnevi & 0. Vesterberg (1977): Plasma levels of lead in arnyotrophic lateral sclerosis and controls, determined by flame-less atomic absorption spectrophotometry. J. Neurol, Neurosurg. Psychiat. (in press). Currier, F. D. & A. F. Haerer (1968): Amyotrophic lateral sclerosis. Arch. Environm Health 17, 712-719. Felmus, M. T., B. M. Patten & L. Swanke (1976): Antecedent events in amyotrophic lateral sclerosis. Neurology 26, 167-172. Griffin, E. M. & W. R. Matson (1972): The assessment of individual variability to trace metal insult: Low-molecular-weight metal complexing agents as indicators of trace metal insult. Amer. Indust. Hyg. Ass. J. 33, 373-377. Kjellin, K. G. & H. Stibler (1976): Isoelectric focusing and electrophoresis of cerebrospinal fluid proteins in muscular dystrophies and spinal muscular atrophies. J. Neurol. Sci. 27, 45-57. Kniffer, I. C. & D. T. Quick (1969): Skeletal muscle capillary abnormalities in amyotrophic lateral sclerosis. Neurology 19, 312-313. Kristensson, K. (1970): Transport of fluorescent protein tracer in peripheral nerves. Acta Neuropathol. 16, 292-300. Kristensson, K. (1975): Retrograde axonal transport of protein tracers. In: The use of axonal transport for studies of neuronal connectivity. Cowan, W. M. & M. Cuenoci (eds.). Elsevier.
261 Kristensson, K. & Y . Olsson (1971): Uptake and retrograde axonal transport of peroxidase in hypoglossal neurones. Acta Neuropath. (Berl.) 19, 1-9. Pawing, H.-H. & F. Gyntelberg (1973): Transcapillary escape rate of albumin and plasma volume in essential hypertension. Circulation Res. 32, 643-651. Ronnevi, L.-O., J. Bystrom, E. Eriksson & L. Ottova (1973): Quantitative distribution of tetanus toxin in peripheral nerves and central nervous system. Europ. Surg. Res. 5, 401-413. Stockel, K., M. Schwab & H. Thoenen (1975): Comparison between the retrograde axonal transport of nerve growth factor and tetanus toxin in motor, sensory and adrenergic neurons. Brain Res. 99, 1-16. Stortebecker, P.. G. Nwdstrom, M. Pap de PestBny, T. Seeman .& S. Bjorkemd (1970): Vascular and metabolic studies of amyotrophic lateral sclerosis. Part I. Angiopathy in biopsy specimens of peripheral arteries. Neurology 20, 1157-1160. Walker, W. G., R. S. Ross & J. D. S. Hammond (1960): Study of the relationship between plasma volume and transcapillary protein exchange using 1311-labeled albumin and 1251-labeledglobulin. Circulation Res. 8, 1028-1040. Wasserman, K. & H. S. Mayerscm (1951): Exchange of albumin between plasma and lymph. Amer. J. Physiol. 165, 15-26. Received November 28, accepted December 1, 1977
S . Conradi, M.D. Department of Clinical Neurology Karolinska Sjukhuset 104 01 Stockholm 60 Sweden
SHORT COMMUNICATION
Depts. of Clinical Neurology and Clinical Physiology, Karolinska Sjukhuset, Dept. of Anatomy, Karolinska Institutet, Stockholm, Sweden
Capillary permeability in ALS, determined through transcapillary escape rate of "sI-albumin
s. CONRADI, L. KAIJSERA N D L.-o. RONNEVI Since various macromolecules have experimentally been demonstrated to be taken u p by the motor end-plates and subsequently transported through retrograde axoplasmic flow, noxious substances may gain entrance to the lower motorneurons through the same route. Consequently, the function of the capillary barrier in skeletal muscle is of interest in diseases of the lower motorneurons. The transcapillary escape rate of 1251-albuminwas determined in six ALS patients. The values fell within the range earlier reported for normals. INTRODUCTION The retrograde axoplasmic flow of the lower motorneurons may have pathogenetic significance in diseases of the motomeurons. Certain macromolecules, such as albumin and horseradish peroxidase have been demonstrated t o be taken up by motor endplates and transported intraaxonally to the motorneuron cell bodies in spinal cord and brain stem (Kristensson 1970, Kristensson & Olsson 1971, Stockel et al. 1975). There is experimental evidence that substances capable of damaging the motorneurons can be transported through the same route (see Kristensson 1975, Ronnevi et al. 1973). This focuses the interest on the function of the capillary b a m e r in skeletal muscle as a protection of the end-plates and thereby the motorneurons against various potentially noxious substances in blood. The present study deals with the capillary permeability of albumin in amyotrophic lateral sclerosis (ALS), determined through the transcapillary escape rate of lZ5Ilabeled human serum albumin (TERald, according to Parving & Gyntelberg (1973). There are earlier reports on capillary abnormalities occurring in ALS, based on histological studies (Kniffer & Quick 1969, Stortebecker et at. 1970) and quantitative studies of CSF proteins (Kjellin & Stibler 1976). MATERIAL AND METHODS Six patients with ALS were studied. The diagnoses were settled by conventional clinical methods, and the patients showed either predominantly peripheral, bulbar or pyramidal symptoms. None of the patients had clinical signs of diabetes, malignancy or hypertension. The transcapillary escape rate was determined according to Parving & Gyntelberg by measuring '=I-activity in venous plasma samples without stasis before and at 15-min intervals during the first hour after intravenous administration of the substance. Mean dilution rate of the albumin was then calculated, assuming a mono-
Born
1922
1928
1932
1934
1922
1943
Sex
M
M
M
F
F
F
Name
W.B.
G.B.
S.R.
G.S.
S.J.
E.S.
1973
1974
1971
1972
1971
N
58
1972
47
52
40
57
61
Weight (kg)
OnSet
Year of
16.0
25
-
29.5
38.9
38.6
33.7
[Alb.]/CSF (mg/100 ml)
3.3
3.9
3.9
4.3
5.1
4.2
(1)
2.1
2.5
2.6
2.7
3.3
2.4
Plasma volume (1)
Table 1 . Details of the measurements on the individual patients
146
151
132
5.3
5.1
5.9
5.7
4.5
4.0
(%I
TER,,dl
Mean 5.1 Normal 5.6 f 1.1
43
43
40
43
44
152 145
48
(%I
Hematocrit
166
Hemoglobin
00
VI
h)
25 9 exponential escape. Blood and plasma volumes were estimated from the pre- and 15-min post-injection activity of whole blood and plasma samples separately. The values given for blood volume were corrected for the difference in venous and mean body hematocrit, assuming that the body hematocrit was 0.91 X the venous hematocrit. In order to obtain an additional measure of capillary function, [albumidCSF was also calculated through paper electrophoresis. Table 1 shows the various measurements.
RESULTS As seen in Table 1, the values for TER,,, in the ALS group are in the same order of size or lower than in normals. Since the extravasation of albumin is closely related to plasma volume (Walker et al. 1960), the correlation between these parameters was also studied (Fig. 1). Likewise, the vaIues from the ALS patients are found within the normal range. Half of the ALS cases showed slightly elevated [albumin]/CSF (> 30 mg/100 ml), but there seemed to be no correlation between these values and TERa,h'
DISCUSSION The iodated albumin can be considered t o behave like endogenous albumin (Parving & Gyntelberg 1973). Further, the disappearance of albumin from blood during the first hour after the infusion has been shown t o reflect - practically totally - the extravasation to interstitial fluid, rather than degradation and excretion (see also Wasserman & Mayerson 1951). The method does, however, not permit differentiation between extravasation of the albumin in muscle and in other tissues. Important factors determining the transcapillary escape rate of albumin in normals are plasma volume and body weight (Walker et al. 1960). Despite the fact that several of the patients had undergone a pronounced loss of weight during the course of the disease, it can be seen that the levels of plasma volumdkg body weight in the patient group did not deviate from normal to, any noticeabmle extent.
TER
alb.
( per cent
/ hour
)
10 1
Plasma volume ( ml / kg
)
Figure I . Relation between TER,,, and plasma volume in the individual ALS patients (circles). Regression lines are for normal subjects (striped) and patients with hypertension (solid), according to Parving & Gyntelberg (1973).
260 Thus, the overall transcapillary escape rate of albumin was found to be normal in the actual ALS patients, although the method previously has permitted the demonstration of an increased escape rate in patients with hypertension (Parving & Gyntelberg 1973). Since albumin is the dominating osmotic factor at the capillary level, it can furthermore be supposed that there ought to be no drastic abnormalities of the bulk flow of plasma across the capillary walls in ALS. There may, of course, be restricted capillary permeability changes, which cannot be demonstrated with the present method. Regarding potentially noxious substances in plasma in ALS, we are currently investigating the turnover and tissue distribution of lead, since there are several earlier reports on overexposure to lead in ALS (Currier & Haerer 1968, Campbell et al. 1970, Felrnus et al. 1976). Our primary interest is devoted to the question of availability of this metal to the motor end-plates (see Conradi et al. 1976, 1977). The binding of lead in plasma is not known in detail, although it has been claimed that the metal is bound t o bo'th small molecules, such as polypeptides, and larger ones, possibly albumin (Griffin & Matson 1972). Concerning lead in ALS, the present findings therefore seem to increase the interest for further studies on the mechanisms of binding 04 the metal to various plasma constituents.
ACKNOWLEDGMENT The studies were supported by Stiftelsen MS-Fonden. REFERENCES Campbell, A. M. G., E. R. Williams & D. Barltsop (1970): Motor neuron disease and exposure to lead. J. Neurol. Neurosurg. Psychiat. 33, 877-885. Conradi, S., L.-0. Ronnevi & 0.Vesterberg (1976): Abnormal tissue distribution of lead in amyotrophic lateral sclerosis. J. Neurol. Sci 29, 259-265. Conradi, S., L.-0. Ronnevi & 0. Vesterberg (1977): Plasma levels of lead in arnyotrophic lateral sclerosis and controls, determined by flame-less atomic absorption spectrophotometry. J. Neurol, Neurosurg. Psychiat. (in press). Currier, F. D. & A. F. Haerer (1968): Amyotrophic lateral sclerosis. Arch. Environm Health 17, 712-719. Felmus, M. T., B. M. Patten & L. Swanke (1976): Antecedent events in amyotrophic lateral sclerosis. Neurology 26, 167-172. Griffin, E. M. & W. R. Matson (1972): The assessment of individual variability to trace metal insult: Low-molecular-weight metal complexing agents as indicators of trace metal insult. Amer. Indust. Hyg. Ass. J. 33, 373-377. Kjellin, K. G. & H. Stibler (1976): Isoelectric focusing and electrophoresis of cerebrospinal fluid proteins in muscular dystrophies and spinal muscular atrophies. J. Neurol. Sci. 27, 45-57. Kniffer, I. C. & D. T. Quick (1969): Skeletal muscle capillary abnormalities in amyotrophic lateral sclerosis. Neurology 19, 312-313. Kristensson, K. (1970): Transport of fluorescent protein tracer in peripheral nerves. Acta Neuropathol. 16, 292-300. Kristensson, K. (1975): Retrograde axonal transport of protein tracers. In: The use of axonal transport for studies of neuronal connectivity. Cowan, W. M. & M. Cuenoci (eds.). Elsevier.
261 Kristensson, K. & Y . Olsson (1971): Uptake and retrograde axonal transport of peroxidase in hypoglossal neurones. Acta Neuropath. (Berl.) 19, 1-9. Pawing, H.-H. & F. Gyntelberg (1973): Transcapillary escape rate of albumin and plasma volume in essential hypertension. Circulation Res. 32, 643-651. Ronnevi, L.-O., J. Bystrom, E. Eriksson & L. Ottova (1973): Quantitative distribution of tetanus toxin in peripheral nerves and central nervous system. Europ. Surg. Res. 5, 401-413. Stockel, K., M. Schwab & H. Thoenen (1975): Comparison between the retrograde axonal transport of nerve growth factor and tetanus toxin in motor, sensory and adrenergic neurons. Brain Res. 99, 1-16. Stortebecker, P.. G. Nwdstrom, M. Pap de PestBny, T. Seeman .& S. Bjorkemd (1970): Vascular and metabolic studies of amyotrophic lateral sclerosis. Part I. Angiopathy in biopsy specimens of peripheral arteries. Neurology 20, 1157-1160. Walker, W. G., R. S. Ross & J. D. S. Hammond (1960): Study of the relationship between plasma volume and transcapillary protein exchange using 1311-labeled albumin and 1251-labeledglobulin. Circulation Res. 8, 1028-1040. Wasserman, K. & H. S. Mayerscm (1951): Exchange of albumin between plasma and lymph. Amer. J. Physiol. 165, 15-26. Received November 28, accepted December 1, 1977
S . Conradi, M.D. Department of Clinical Neurology Karolinska Sjukhuset 104 01 Stockholm 60 Sweden
