Int Arch Occup Environ Health (1990) 62:177-181
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Upafonal-nd
Environmental health
© Springer-Verlag 1990
Responses of sympathetic nervous system to cold exposure in vibration syndrome subjects and age-matched healthy controls Minoru Nakamoto Department of Public Health, Ehime University School of Medicine, Shigenobu, Ehime 791-02, Japan Received August 12 / Accepted November 11, 1989
Summary Plasma norepinephrine and epinephrine in vibration syndrome subjects and age-matched healthy controls were measured for the purpose of estimating the responsibility of the sympathetic nervous system to cold exposure In preliminary experiment, it was confirmed that cold air exposure of the whole body was more suitable than one-hand immersion in cold water In the main experiment, 195 subjects were examined Sixty-five subjects had vibration syndrome with vibration-induced white finger (VWF+ group) and 65 subjects had vibration syndrome without VWF (VWF group) and 65 controls had no symptoms (control group) In the three groups, plasma norepinephrine levels increased during cold air exposure of whole body at 7 ° + 1 5 °C Blood pressure increased and skin temperature decreased during cold exposure Percent increase of norepinephrine in the VWF+ group was the highest while that in VWF group followed and that in the control group was the lowest This whole-body response of the sympathetic nervous system to cold conditions reflected the VWF which are characteristic symptoms of vibration syndrome Excluding the effects of shivering and a cold feeling under cold conditions, it was confirmed that the sympathetic nervous system in vibration syndrome is activated more than in the controls These results suggest that vibration exposure to hand and arm affects the sympathetic nervous system. Key words: Norepinephrine Epinephrine Blood pressure Skin temperature Vibration-induced white finger
Introduction Vibration-induced white finger appears easily when vibration syndrome patients are exposed to cold, especially in winter The feeling of cold in their extremities increases under cold conditions These facts suggest that the vibration syndrome patients are more sensitive to cold than healthy persons Several investigators have
measured urinary and plasma catecholamines in vibration syndrome subjects; however, no definite conclusion has been reached lNasu et al 1975 ; Miyashita et al 1983 ; Itoh 1984; Bovensi 1986 ; Saito et al 1986 ; Une and Esaki 1988l. From the new methods and instruments of measurements which have been recently developed, measurements of plasma and urinary catecholamines (norepinephrine and epinephrine) are now widely used to assess the function of the sympathetic nervous system The method developed by Nagatsu and his coworkers is relatively easy and effective for measuring plasma norepinephrine and epinephrine lMaruta et al 1984 ; Nagatsu and Kojima 1988 l To compare the response of the sympathetic nervous system to cold exposure in vibration syndrome subjects with healthy controls, plasma norepinephrine and epinephrine of 195 subjects were measured in this study.
Materials and methods Preliminary experiment Three young male subjects who were healthy laboratory workers (mean age 34 years) were seated resting in a room at 25°C for 60min Then one hand was immersed in cold water at 5 °C for 10 min The subjects rested again for 60 min. Then they changed to a room maintained at 10°C and remained seated for 30 min, after which they returned to the 25 °C room At intervals during this experiment, blood samples were taken thirteen times from a catheterized vein of the forearm opposite the immersed side Each subject wore an undershirt, underpants, a shirt, trousers and socks. Main experiment One hundred ninety-five male subjects were examined Sixty-five of these subjects had vibration syndrome and vibration-induced white finger (VWF+ group, mean age 55 9 ± 5 6 years, mean time exposed to vibration 21400 ± 15500 h) The frequencies of their white finger attacks were more than four times a month in the previous winter Another 65 subjects had vibration syndrome but did not have vibration-induced white finger (VWFgroup, 55 9 ± 5 9 years, 13900 ± 9100 h) The remaining 65 subjects had no symptoms (control group, 55 7 6 0 years) These three groups were individually matched by age They had no complications of serious illness, for example, hypertension, diabetes mellitus, cerebrovascular disease, heart disease, anemia, liver dis-
178 2
I
pg/m
ease, pneumoconiosis and others Their medications were stopped more than a week before in the VWF+ and VWF groups. They were seated in a room maintained at 7° + 1 50 C after resting in a 25°C room Blood samples were taken at 25 min during a 30-min rest and again at 25 min during a 30-min exposure in the cold room They wore the same kind of clothes as in the preliminary experiment Blood pressure of the arm and skin temperature of the right middle finger were measured before taking blood samples during rest and cold exposure conditions. This experiment was carried out before noon to avoid influences of the circadian rhythm The subjects were examined from October 1987 to March 1988.
ll
I
I OO o
500
O3 1 O
3 O
O
O3
O
I5 O
Measurement of catecholamines and statisticalmethods Plasma was stored at -80 0 C until measurement and norepinephrine and epinephrine were analysed by high-performance liquid chromatography (HPLC) with the trihydroxy indole (THI) method Before injecting to HPLC nlasma noreninephrine and eninephrine were purified by alumina in the preliminary experiment However in the main experiment, borate gel was used for purification lMaruta et al 1984 ; Nagatsu and Kojima 1988 l The paired t-test, the Stu-
mi N
Fig 1 Preliminary experiment: change of plasma norepinephrine mean level (pg/ml) in healthy subjects (n = 3) under one hand immersion in cold water at 5 C and whole body exposure to cold air at 10°C
Table 1 Skin temperature of the middle finger during rest at 25 °C and during cold air exposure at 7° + 1 5°C Values are given as the mean and standard deviation (C) n
Rest
Exposure
Difference
VWF+
65
32 6 ± 2 7*
17 0 + 2 2** -15 6 + 2 2*
VWF
65
32 5 + 1 8
18 4 + 2 2
-15 1 ± 2 2
## Control
65
33 6 + 1 9
18 9 + 2 5
-14 6 ± 2 6
## Significant from controls: * P
InternationalArchivesof
O
Upafonal-nd
Environmental health
© Springer-Verlag 1990
Responses of sympathetic nervous system to cold exposure in vibration syndrome subjects and age-matched healthy controls Minoru Nakamoto Department of Public Health, Ehime University School of Medicine, Shigenobu, Ehime 791-02, Japan Received August 12 / Accepted November 11, 1989
Summary Plasma norepinephrine and epinephrine in vibration syndrome subjects and age-matched healthy controls were measured for the purpose of estimating the responsibility of the sympathetic nervous system to cold exposure In preliminary experiment, it was confirmed that cold air exposure of the whole body was more suitable than one-hand immersion in cold water In the main experiment, 195 subjects were examined Sixty-five subjects had vibration syndrome with vibration-induced white finger (VWF+ group) and 65 subjects had vibration syndrome without VWF (VWF group) and 65 controls had no symptoms (control group) In the three groups, plasma norepinephrine levels increased during cold air exposure of whole body at 7 ° + 1 5 °C Blood pressure increased and skin temperature decreased during cold exposure Percent increase of norepinephrine in the VWF+ group was the highest while that in VWF group followed and that in the control group was the lowest This whole-body response of the sympathetic nervous system to cold conditions reflected the VWF which are characteristic symptoms of vibration syndrome Excluding the effects of shivering and a cold feeling under cold conditions, it was confirmed that the sympathetic nervous system in vibration syndrome is activated more than in the controls These results suggest that vibration exposure to hand and arm affects the sympathetic nervous system. Key words: Norepinephrine Epinephrine Blood pressure Skin temperature Vibration-induced white finger
Introduction Vibration-induced white finger appears easily when vibration syndrome patients are exposed to cold, especially in winter The feeling of cold in their extremities increases under cold conditions These facts suggest that the vibration syndrome patients are more sensitive to cold than healthy persons Several investigators have
measured urinary and plasma catecholamines in vibration syndrome subjects; however, no definite conclusion has been reached lNasu et al 1975 ; Miyashita et al 1983 ; Itoh 1984; Bovensi 1986 ; Saito et al 1986 ; Une and Esaki 1988l. From the new methods and instruments of measurements which have been recently developed, measurements of plasma and urinary catecholamines (norepinephrine and epinephrine) are now widely used to assess the function of the sympathetic nervous system The method developed by Nagatsu and his coworkers is relatively easy and effective for measuring plasma norepinephrine and epinephrine lMaruta et al 1984 ; Nagatsu and Kojima 1988 l To compare the response of the sympathetic nervous system to cold exposure in vibration syndrome subjects with healthy controls, plasma norepinephrine and epinephrine of 195 subjects were measured in this study.
Materials and methods Preliminary experiment Three young male subjects who were healthy laboratory workers (mean age 34 years) were seated resting in a room at 25°C for 60min Then one hand was immersed in cold water at 5 °C for 10 min The subjects rested again for 60 min. Then they changed to a room maintained at 10°C and remained seated for 30 min, after which they returned to the 25 °C room At intervals during this experiment, blood samples were taken thirteen times from a catheterized vein of the forearm opposite the immersed side Each subject wore an undershirt, underpants, a shirt, trousers and socks. Main experiment One hundred ninety-five male subjects were examined Sixty-five of these subjects had vibration syndrome and vibration-induced white finger (VWF+ group, mean age 55 9 ± 5 6 years, mean time exposed to vibration 21400 ± 15500 h) The frequencies of their white finger attacks were more than four times a month in the previous winter Another 65 subjects had vibration syndrome but did not have vibration-induced white finger (VWFgroup, 55 9 ± 5 9 years, 13900 ± 9100 h) The remaining 65 subjects had no symptoms (control group, 55 7 6 0 years) These three groups were individually matched by age They had no complications of serious illness, for example, hypertension, diabetes mellitus, cerebrovascular disease, heart disease, anemia, liver dis-
178 2
I
pg/m
ease, pneumoconiosis and others Their medications were stopped more than a week before in the VWF+ and VWF groups. They were seated in a room maintained at 7° + 1 50 C after resting in a 25°C room Blood samples were taken at 25 min during a 30-min rest and again at 25 min during a 30-min exposure in the cold room They wore the same kind of clothes as in the preliminary experiment Blood pressure of the arm and skin temperature of the right middle finger were measured before taking blood samples during rest and cold exposure conditions. This experiment was carried out before noon to avoid influences of the circadian rhythm The subjects were examined from October 1987 to March 1988.
ll
I
I OO o
500
O3 1 O
3 O
O
O3
O
I5 O
Measurement of catecholamines and statisticalmethods Plasma was stored at -80 0 C until measurement and norepinephrine and epinephrine were analysed by high-performance liquid chromatography (HPLC) with the trihydroxy indole (THI) method Before injecting to HPLC nlasma noreninephrine and eninephrine were purified by alumina in the preliminary experiment However in the main experiment, borate gel was used for purification lMaruta et al 1984 ; Nagatsu and Kojima 1988 l The paired t-test, the Stu-
mi N
Fig 1 Preliminary experiment: change of plasma norepinephrine mean level (pg/ml) in healthy subjects (n = 3) under one hand immersion in cold water at 5 C and whole body exposure to cold air at 10°C
Table 1 Skin temperature of the middle finger during rest at 25 °C and during cold air exposure at 7° + 1 5°C Values are given as the mean and standard deviation (C) n
Rest
Exposure
Difference
VWF+
65
32 6 ± 2 7*
17 0 + 2 2** -15 6 + 2 2*
VWF
65
32 5 + 1 8
18 4 + 2 2
-15 1 ± 2 2
## Control
65
33 6 + 1 9
18 9 + 2 5
-14 6 ± 2 6
## Significant from controls: * P
