- Email: [email protected]
Post-heparin hepatic lipase activity and plasma high density lipoprotein levels in men during physical training
BIOCHEMICAL
MEDICINE
31, 31-35 (1984)
Post-heparin Hepatic Lipase Activity and Plasma High Density Lipoprotein Levels in Men during Physical Training’ W. H. F. SUTHERLAND,
S. P. WOODHOUSE, AND D. F. GERARD
Department
of Medicine,
University
of Otago
Medical
School,
E. R. NYE, Dunedin,
New
Zealand
Received January 5, 1983
Previous studies (1,2) have suggested that hepatic lipase activity may have a function in the removal of high density lipoprotein lipids from plasma. Physical training in men usually raises high density lipoprotein cholesterol (HDL-C) levels (3,4) but the mechanisms underlying this change have not been fully elucidated. One possibility is that hepatic lipase activity decreases with training resulting in an increase in HDLC. In support of this proposal lower levels of post-heparin hepatic lipase (PHHL) activity were found in physically well-trained men compared to sedentary men (5) and this activity has been correlated inversely with plasma HDL-C levels in man (1,6). However, a longitudinal study (6) did not show a significant decrease in PHHL activity accompanying a small increase in plasma HDL-C levels with moderate training. In the present investigation we have measured PHHL activity and plasma HDLC levels in men training for their first marathon run. Based on results from our earlier study (3), a more substantial increase in plasma HDLC levels would be expected in these men compared to men who undertook a moderate level of training (6). A pronounced increase in plasma HDLC levels with training should highlight any effect of hepatic lipase on plasma HDL-C revels. SUBJECTS AND METHODS
This study group consisted of 12 partially trained men, ages 18-47, mean age 27. Informed consent was obtained from the men and the project was approved by the Medical Ethics Committee. The men under’ This study was supported by the Medical Research Council of New Zealand, the National Heart Foundation of New Zealand, and the Charles Butterfield Trust. 31 0006-2944/84 $3 .OO Copyright 0 1984 by Academic Press, Inc. All rights of reproduction in any form reserved.
32
SUTHERLAND
ET AL
went an initial health examination including blood pressure, 12-lead electrocardiogram, and fasted blood glucose and plasma lipid levels. The subjects participated in a self-regulated training program of 18 weeks duration to take part in their first marathon run. The sampling times were at the beginning of the study, after 6 and 18 weeks training which was 1 week prior to the marathon run. After a 12-hour fast, blood was collected in tubes containing EDTA and plasma was separated immediately by centrifugation. An aliquot of the plasma was stored at -20” until plasma cholesterol (7) and triglycerides (8) were measured spectrophotometrically. Another volume of plasma was kept at 4” and HDL was isolated from this plasma on the day of collection. HDL-C was determined after precipitation of other lipoproteins with magnesium chloride and sodium phosphotungstate (9). Post-heparin plasma was obtained by injecting heparin (100 lU/kg) intravenously into the fasted subjects and collecting blood (10 ml) at 0, 5, and 15 min. The plasma was immediately isolated from the ice-cold blood and aliquots of the plasma from each time interval were stored at - 80” (10). The samples from each period of the training program were assayed for PHHL activity in one batch. Unless otherwise stated, the levels of PHHL at 15 min after the heparin injection were used in subsequent statistical calculations. Pulse rate at submaximal workload (900 kpm/min) was measured on a bicycle ergometer (11) and, anthropometric data were recorded during the study. Reported weekly distance run was obtained from answers to a questionnaire. RESULTS
Three men dropped out during the study. Injury (one man) and inability to maintain the level of training (two men) were responsible. A final value for PHHL activity was not obtained for one man. The results from these subjects are not included in this report. The mean weekly distance run by the men in training for the marathon run was significantly increased at the end of the study and mean heart rate at 900 kpm/min at this time was significantly lower than the initial value. On the other hand mean body weight did not change significantly with training. These results are summarized in Table 1. Mean plasma HDL-C concentration was not significantly altered by 6 weeks training but was raised by 27% after 18 weeks of physical training. In contrast, plasma levels of cholesterol and triglycerides did not move significantly from initial values during the study. These results are shown in Table 2. The coefficient of variation for duplicate analyses of PHHL activity was 4% (n = 6) and activities at 5 min after the administration of heparin were not significantly different from the corresponding values after 15 min. A significant (P < 0.05) inverse correlation was observed between
EXERCISE,
HDL, AND HEPATIC
33
LIPASE
TABLE 1 BODY WEIGHT, HEART RATE AT SUBMAXIMAL WORK AND REWRTED DISTANCE RUN BY MEN BEFOREAND AFTER 18 WEEKS TRAINING FORA MARATHON RUN Before Body weight (kg) Heart rate at submaximal work (beatslmin) Repotted weekly distance run (km)
78.3 143
After
‘_ 3.1
2 5.0
79.0
-t 6
-c 3h
130
19 + 3
52
+ 16"
Note. Data are means 2 SEM, n = 8. ” A significant difference of KO.05 compared to initial values. b A significant difference of P
pretraining values of PHHL activity and HDL-C levels in plasma (r = 0.733, n = 8). Eighteen weeks of physical training raised PHHL activity (I 5 min values) by 29% (Table 3). DISCUSSION
Similarly to the findings in our previous marathon training study (3) the present results show that aerobic fitness increased, plasma HDL-C levels increased and body weight did not change significantly in men after training for a marathon run (Tables 1 and 2). PHHL activity had increased in these men after 18 weeks training (Table 3) which was an unexpected finding since a previous study showed that this activity was lower in men who were physically well-trained compared to sedentary men (5). However, another longitudinal study (6) also failed to demonstrate reduced PHHL activity in men with training. In the present study it is possible that initial levels of PHHL activity were already low in these partially conditioned men. Nevertheless, the pretraining levels of PHHL activity seen here (Table 3) were substantially higher than values reported for well-trained men (5) and were comparable to levels previously recorded in healthy young men and women (12) and in sedentary men (6). On the TABLE 2 PLASMA LJPIDS AND HIGH DENSITY LIPOPROTEINCHOLESTEROL(HDL-C) LEVELS IN MEN DURING18 WEEKS TRAINING FORA MARATHON RUN Plasma lipids (mmolel I) Cholesterol Triglycerides HDL-C
________ 0 __~..--. 6.19 i 0.18 1.07 2 0.10 1.49 -r- 0.14
Weeks of the study --.___ 6 .--____ 5.69 rtr 0.28 0.95 t 0.15 1.50 t 0.14
Note. Data are means % SEM, n = 8. ” A significant difference of PiO.05 compared to initial values.
18 2 0.46 2 0.10 1.89 2 0.22
6.38 1.21
34
SUTHERLAND
ET AL
TABLE
3
POST-HEPARIN HEI’ATIC LIPASE (PHHL) ACTIVITY IN THE PLASMA OF MEN DURING 18 WEEKS TRAINING FOR A MARATHOK KV,Y
PHHL activity (hmole FFAimlihr) Weeks of the study
5 min”
IS min
0 15.5 ” 1.4 15.7 + 1.4 6 14.2 k 1.6 16.2 k I.9 18 18.6 -r- 2.8” 20.3 2 3.1b __ ~-..--~~~ --~~~~~- .~~-~~~ ~~~ -.~ Note. Data are means ? SEM, n = 8. ’ Time elapsed after the intravenous injection of heparin into the subjects. b A significant difference of P < 0.0.5 compared to initial values.
other hand, the present levels of PHHL activity were also considerably lower than those which were previously found in another group of young men (10). Overall, the effect of physical training on PHHL activity is not yet well defined. The inverse correlation between levels of PHHL activity and plasma HDL-C seen here agrees with the results in previous studies (1,6). This correlation has been attributed to the catabolism of HDL by hepatic lipase (1) and to the inhibitory effect of HDL on PHHL activity (13,14). If these variables were connected by a cause-effect relationship and other factors did not markedly influence them, then an increase in plasma HDL-C levels with training should be accompanied by reduced levels of PHHL activity. The increase in PHHL activity in the face of a substantial rise in plasma HDL-C levels (Tables 2 and 3) is contrary to this scheme. Hence in conjunction with the previous finding of unchanged PHHL activity with training (6), our results cast doubt on the proposal that reduced PHHL activity contributes substantially to increased plasma HDL-C levels with physical training. Whether an increase in plasma HDL-C with regular physical training, as was seen in the present study (Table 2), reduces risk of developing coronary heart disease (CHD) in men is uncertain. Thus in spite of an inverse relationship between plasma HDL-C levels and incidence of CHD in populations (15,16) there is little if any evidence to show that raising plasma HDL-C levels reduces the incidence of the disease. Nevertheless epidemiological data suggest that the overall effect of regular physical training is to reduce the risk of developing CHD (17.18).
EXERCISE,
HDL, AND HEPATlC
LIPASE
35
SUMMARY Plasma post-heparin hepatic lipase (PHHL) activity, plasma lipids, and high density lipoprotein cholesterol (HDL-C) levels, pulse rate at submaximal workload, and body weight were measured in 12 men during the 18 weeks physical training for their first marathon run. Reduced pulse rate at submaximal workload indicated that the men increased their physical fitness during the training period. Plasma HDLC levels ( + 27%) and PHHL activity ( + 29%) also increased significantly after 18 weeks training. These changes were not in accord with the inverse correlation between plasma HDL-C levels and PHHL activity which was observed before training. The results of this study do not support the concept that reduced PHHL activity is mainly responsible for increased levels of plasma HDL-C with training. ACKNOWLEDGMENTS The authors thank Dr. P. French and Dr. M. Matangi, also Mr. B. Smith, Mrs. J. G&ins, Mrs. P. Mason, and Mrs. S. Williamson for excellent technical assistance. The cooperation of the participants in the study is also gratefully acknowledged.
REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18.
Kuusi, T., Saarinen, P., and Nikkill, E. A., Atherosclerosis 36, 589 (1980). Kuusi, T., Kinnumen, P. K. J., and Nikkile, E. A., FEB.9 Lerr. 104, 384 (1979). Sutherland, W. H. F., and Woodhouse, S. P., Atherosclerosis 37, 285 (1980). Alterkruse, E. N., and Wilmore, J. H., J. Oct. Med. 15, 110 (1973). Marniemi, J., Peltonen, P.. Vuori, I., and Hietanen, E., Acta Physiol. &and. 110, 131 (1980). Peltonen, P., Marniemi, J., Hietanen, E., Vuori, I.. and Ehnholm, C., Metabolism 30, 518 (1981). Abell, I. L., Levy, B. B., Brodie, B. B., and Kendall, F. E., J. Biol. Chem. 195, 357 (1952). Carlson, L. A., J. Atheroscler. Res. 3, 334 (1963). Lopes-Virella, M. F., Stone, P., Ellis, S., and Colwell. J. A., Clin. Chem. 23, 882 (1977). Huttunen, J. K., Ehnholm. C., Kinnumen, P. K. J., and Nikkila, E. A., Cfin. Chim. Actu 63, 335 (1975). Astrand, P-O., and Rhyming, I., J. Appl. Physiol. 7, 218 (1954). Nilsson-Ehle, P. O., and Ekman, R., Artery 3, 194 (1977). Kinnumen, P. K. J., Vainio, P., and Thuren, T., Afherosclerosis 40, 377 (1981). Bengtsson, G., and Olivecrona, T., FEES Letr. 119, 290 (1980). Miller, N. E., Forde, 0. H., Thelle, D. S., and Mjos, 0. D., Lancer i %5 (1977). Castelli, W. P., Doyle, J. T., Gordon, T., Hanes, C. G., Hjortland, M. C., Hulley, S. B., Kagan, A., and Zukel, W. J., Circulation 55, 767 (1977). Morris, J. H., Chave, S. P. W., Adam, C., Sirey. C.. Epstein, L., and Sheehan, D. J., Luncet i, 333 (1973). Paffenbarger, R. S., and Hale, W. E., N. Engl. J. Med. 292, 545 (1975).
MEDICINE
31, 31-35 (1984)
Post-heparin Hepatic Lipase Activity and Plasma High Density Lipoprotein Levels in Men during Physical Training’ W. H. F. SUTHERLAND,
S. P. WOODHOUSE, AND D. F. GERARD
Department
of Medicine,
University
of Otago
Medical
School,
E. R. NYE, Dunedin,
New
Zealand
Received January 5, 1983
Previous studies (1,2) have suggested that hepatic lipase activity may have a function in the removal of high density lipoprotein lipids from plasma. Physical training in men usually raises high density lipoprotein cholesterol (HDL-C) levels (3,4) but the mechanisms underlying this change have not been fully elucidated. One possibility is that hepatic lipase activity decreases with training resulting in an increase in HDLC. In support of this proposal lower levels of post-heparin hepatic lipase (PHHL) activity were found in physically well-trained men compared to sedentary men (5) and this activity has been correlated inversely with plasma HDL-C levels in man (1,6). However, a longitudinal study (6) did not show a significant decrease in PHHL activity accompanying a small increase in plasma HDL-C levels with moderate training. In the present investigation we have measured PHHL activity and plasma HDLC levels in men training for their first marathon run. Based on results from our earlier study (3), a more substantial increase in plasma HDLC levels would be expected in these men compared to men who undertook a moderate level of training (6). A pronounced increase in plasma HDLC levels with training should highlight any effect of hepatic lipase on plasma HDL-C revels. SUBJECTS AND METHODS
This study group consisted of 12 partially trained men, ages 18-47, mean age 27. Informed consent was obtained from the men and the project was approved by the Medical Ethics Committee. The men under’ This study was supported by the Medical Research Council of New Zealand, the National Heart Foundation of New Zealand, and the Charles Butterfield Trust. 31 0006-2944/84 $3 .OO Copyright 0 1984 by Academic Press, Inc. All rights of reproduction in any form reserved.
32
SUTHERLAND
ET AL
went an initial health examination including blood pressure, 12-lead electrocardiogram, and fasted blood glucose and plasma lipid levels. The subjects participated in a self-regulated training program of 18 weeks duration to take part in their first marathon run. The sampling times were at the beginning of the study, after 6 and 18 weeks training which was 1 week prior to the marathon run. After a 12-hour fast, blood was collected in tubes containing EDTA and plasma was separated immediately by centrifugation. An aliquot of the plasma was stored at -20” until plasma cholesterol (7) and triglycerides (8) were measured spectrophotometrically. Another volume of plasma was kept at 4” and HDL was isolated from this plasma on the day of collection. HDL-C was determined after precipitation of other lipoproteins with magnesium chloride and sodium phosphotungstate (9). Post-heparin plasma was obtained by injecting heparin (100 lU/kg) intravenously into the fasted subjects and collecting blood (10 ml) at 0, 5, and 15 min. The plasma was immediately isolated from the ice-cold blood and aliquots of the plasma from each time interval were stored at - 80” (10). The samples from each period of the training program were assayed for PHHL activity in one batch. Unless otherwise stated, the levels of PHHL at 15 min after the heparin injection were used in subsequent statistical calculations. Pulse rate at submaximal workload (900 kpm/min) was measured on a bicycle ergometer (11) and, anthropometric data were recorded during the study. Reported weekly distance run was obtained from answers to a questionnaire. RESULTS
Three men dropped out during the study. Injury (one man) and inability to maintain the level of training (two men) were responsible. A final value for PHHL activity was not obtained for one man. The results from these subjects are not included in this report. The mean weekly distance run by the men in training for the marathon run was significantly increased at the end of the study and mean heart rate at 900 kpm/min at this time was significantly lower than the initial value. On the other hand mean body weight did not change significantly with training. These results are summarized in Table 1. Mean plasma HDL-C concentration was not significantly altered by 6 weeks training but was raised by 27% after 18 weeks of physical training. In contrast, plasma levels of cholesterol and triglycerides did not move significantly from initial values during the study. These results are shown in Table 2. The coefficient of variation for duplicate analyses of PHHL activity was 4% (n = 6) and activities at 5 min after the administration of heparin were not significantly different from the corresponding values after 15 min. A significant (P < 0.05) inverse correlation was observed between
EXERCISE,
HDL, AND HEPATIC
33
LIPASE
TABLE 1 BODY WEIGHT, HEART RATE AT SUBMAXIMAL WORK AND REWRTED DISTANCE RUN BY MEN BEFOREAND AFTER 18 WEEKS TRAINING FORA MARATHON RUN Before Body weight (kg) Heart rate at submaximal work (beatslmin) Repotted weekly distance run (km)
78.3 143
After
‘_ 3.1
2 5.0
79.0
-t 6
-c 3h
130
19 + 3
52
+ 16"
Note. Data are means 2 SEM, n = 8. ” A significant difference of KO.05 compared to initial values. b A significant difference of P
pretraining values of PHHL activity and HDL-C levels in plasma (r = 0.733, n = 8). Eighteen weeks of physical training raised PHHL activity (I 5 min values) by 29% (Table 3). DISCUSSION
Similarly to the findings in our previous marathon training study (3) the present results show that aerobic fitness increased, plasma HDL-C levels increased and body weight did not change significantly in men after training for a marathon run (Tables 1 and 2). PHHL activity had increased in these men after 18 weeks training (Table 3) which was an unexpected finding since a previous study showed that this activity was lower in men who were physically well-trained compared to sedentary men (5). However, another longitudinal study (6) also failed to demonstrate reduced PHHL activity in men with training. In the present study it is possible that initial levels of PHHL activity were already low in these partially conditioned men. Nevertheless, the pretraining levels of PHHL activity seen here (Table 3) were substantially higher than values reported for well-trained men (5) and were comparable to levels previously recorded in healthy young men and women (12) and in sedentary men (6). On the TABLE 2 PLASMA LJPIDS AND HIGH DENSITY LIPOPROTEINCHOLESTEROL(HDL-C) LEVELS IN MEN DURING18 WEEKS TRAINING FORA MARATHON RUN Plasma lipids (mmolel I) Cholesterol Triglycerides HDL-C
________ 0 __~..--. 6.19 i 0.18 1.07 2 0.10 1.49 -r- 0.14
Weeks of the study --.___ 6 .--____ 5.69 rtr 0.28 0.95 t 0.15 1.50 t 0.14
Note. Data are means % SEM, n = 8. ” A significant difference of PiO.05 compared to initial values.
18 2 0.46 2 0.10 1.89 2 0.22
6.38 1.21
34
SUTHERLAND
ET AL
TABLE
3
POST-HEPARIN HEI’ATIC LIPASE (PHHL) ACTIVITY IN THE PLASMA OF MEN DURING 18 WEEKS TRAINING FOR A MARATHOK KV,Y
PHHL activity (hmole FFAimlihr) Weeks of the study
5 min”
IS min
0 15.5 ” 1.4 15.7 + 1.4 6 14.2 k 1.6 16.2 k I.9 18 18.6 -r- 2.8” 20.3 2 3.1b __ ~-..--~~~ --~~~~~- .~~-~~~ ~~~ -.~ Note. Data are means ? SEM, n = 8. ’ Time elapsed after the intravenous injection of heparin into the subjects. b A significant difference of P < 0.0.5 compared to initial values.
other hand, the present levels of PHHL activity were also considerably lower than those which were previously found in another group of young men (10). Overall, the effect of physical training on PHHL activity is not yet well defined. The inverse correlation between levels of PHHL activity and plasma HDL-C seen here agrees with the results in previous studies (1,6). This correlation has been attributed to the catabolism of HDL by hepatic lipase (1) and to the inhibitory effect of HDL on PHHL activity (13,14). If these variables were connected by a cause-effect relationship and other factors did not markedly influence them, then an increase in plasma HDL-C levels with training should be accompanied by reduced levels of PHHL activity. The increase in PHHL activity in the face of a substantial rise in plasma HDL-C levels (Tables 2 and 3) is contrary to this scheme. Hence in conjunction with the previous finding of unchanged PHHL activity with training (6), our results cast doubt on the proposal that reduced PHHL activity contributes substantially to increased plasma HDL-C levels with physical training. Whether an increase in plasma HDL-C with regular physical training, as was seen in the present study (Table 2), reduces risk of developing coronary heart disease (CHD) in men is uncertain. Thus in spite of an inverse relationship between plasma HDL-C levels and incidence of CHD in populations (15,16) there is little if any evidence to show that raising plasma HDL-C levels reduces the incidence of the disease. Nevertheless epidemiological data suggest that the overall effect of regular physical training is to reduce the risk of developing CHD (17.18).
EXERCISE,
HDL, AND HEPATlC
LIPASE
35
SUMMARY Plasma post-heparin hepatic lipase (PHHL) activity, plasma lipids, and high density lipoprotein cholesterol (HDL-C) levels, pulse rate at submaximal workload, and body weight were measured in 12 men during the 18 weeks physical training for their first marathon run. Reduced pulse rate at submaximal workload indicated that the men increased their physical fitness during the training period. Plasma HDLC levels ( + 27%) and PHHL activity ( + 29%) also increased significantly after 18 weeks training. These changes were not in accord with the inverse correlation between plasma HDL-C levels and PHHL activity which was observed before training. The results of this study do not support the concept that reduced PHHL activity is mainly responsible for increased levels of plasma HDL-C with training. ACKNOWLEDGMENTS The authors thank Dr. P. French and Dr. M. Matangi, also Mr. B. Smith, Mrs. J. G&ins, Mrs. P. Mason, and Mrs. S. Williamson for excellent technical assistance. The cooperation of the participants in the study is also gratefully acknowledged.
REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18.
Kuusi, T., Saarinen, P., and Nikkill, E. A., Atherosclerosis 36, 589 (1980). Kuusi, T., Kinnumen, P. K. J., and Nikkile, E. A., FEB.9 Lerr. 104, 384 (1979). Sutherland, W. H. F., and Woodhouse, S. P., Atherosclerosis 37, 285 (1980). Alterkruse, E. N., and Wilmore, J. H., J. Oct. Med. 15, 110 (1973). Marniemi, J., Peltonen, P.. Vuori, I., and Hietanen, E., Acta Physiol. &and. 110, 131 (1980). Peltonen, P., Marniemi, J., Hietanen, E., Vuori, I.. and Ehnholm, C., Metabolism 30, 518 (1981). Abell, I. L., Levy, B. B., Brodie, B. B., and Kendall, F. E., J. Biol. Chem. 195, 357 (1952). Carlson, L. A., J. Atheroscler. Res. 3, 334 (1963). Lopes-Virella, M. F., Stone, P., Ellis, S., and Colwell. J. A., Clin. Chem. 23, 882 (1977). Huttunen, J. K., Ehnholm. C., Kinnumen, P. K. J., and Nikkila, E. A., Cfin. Chim. Actu 63, 335 (1975). Astrand, P-O., and Rhyming, I., J. Appl. Physiol. 7, 218 (1954). Nilsson-Ehle, P. O., and Ekman, R., Artery 3, 194 (1977). Kinnumen, P. K. J., Vainio, P., and Thuren, T., Afherosclerosis 40, 377 (1981). Bengtsson, G., and Olivecrona, T., FEES Letr. 119, 290 (1980). Miller, N. E., Forde, 0. H., Thelle, D. S., and Mjos, 0. D., Lancer i %5 (1977). Castelli, W. P., Doyle, J. T., Gordon, T., Hanes, C. G., Hjortland, M. C., Hulley, S. B., Kagan, A., and Zukel, W. J., Circulation 55, 767 (1977). Morris, J. H., Chave, S. P. W., Adam, C., Sirey. C.. Epstein, L., and Sheehan, D. J., Luncet i, 333 (1973). Paffenbarger, R. S., and Hale, W. E., N. Engl. J. Med. 292, 545 (1975).