Mark A. Kantor

Exercise acutely increases high density lipoprotein-cholesterol and lipoprotein lipase activity in trained and untrained men☆

We studied the effects of a single exercise session on lipid and lipoprotein concentrations and on postheparin plasma lipoprotein lipase (LPLA) and hepatic triglyceride hydrolase activities (HTGLA) in 11 trained (T) and ten untrained (UT) men. Subjects exercised on a bicycle ergometer at 80% of their maximal heart rate for one (UT) or two hours (T). Blood samples were drawn 24 hours before and at ten minutes and 24, 48, and 72 hours after exercise. Values were analyzed before and after adjustment for estimated changes in plasma volume (PV). High density lipoprotein cholesterol (HDL-C) increased 2 +/- 4 mg/dL in T (P less than 0.05) and 1 +/- 2 mg/dL in UT subjects beginning 48 hours after exercise. This increase was magnified by adjusting for the 5% to 8% postexercise expansion of PV. The increase in HDL in the T subjects was produced by increases in the HDL2-C subfraction (+3 +/- 4 mg/dL, P less than 0.05) whereas HDL3 increased in the UT men (+2 +/- 3 mg/dL, P less than 0.05). LPLA did not change in either subject group when estimated PV changes were ignored but increased 11% (P less than 0.05) at 24 hours after exercise when PV was considered. HTGLA was 11% below baseline in the UT men 24 to 72 hours after exercise (P less than 0.05) but showed no change in either subject group after adjustment for PV. These results demonstrate that exercise acutely increases HDL levels by raising the HDL2 subfraction in T and the HDL3 subfraction in UT men.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute increase in lipoprotein lipase following prolonged exercise

Abstract We investigated the acute effects of prolonged exercise on lipoprotein metabolism. Serum lipid and lipoprotein concentrations and plasma postheparin lipolytic activity were measured in ten well-trained men (ages 21 to 39) the day before and after a 42 km foot race. LDL cholesterol decreased by 10% (113 ± 31 to 103 ± 32 mg/dL, P P P P 2 subfraction (37 ± 19 mg/dL, P

Androgens reduce HDL2-cholesterol and increase hepatic triglyceride lipase activity

We quantified serum lipids and postheparin plasma lipolytic activities in 5 weightlifters presently self-administering androgenic steroids (users) and an equal number not currently using these drugs (non-users). Mean (+/- SD) age (23 +/- 2 vs 25 +/- 4 yr), body weight (102.7 +/- 11.4 vs 86.8 +/- 13.6 kg), and percent body fat (8.6 +/- 2.5 vs 7.8 +/- 6.0%) were not different in users and non-users, respectively. Similarly, there were no differences in total cholesterol (183 +/- 27 vs 176 +/- 32 mg.dl-1) low-density lipoprotein-cholesterol (138 +/- 25 vs 108 +/- 32 mg.dl-1), or triglyceride (93 +/- 26 vs 93 +/- 41 mg.dl-1) levels in the two groups. High-density lipoprotein (HDL)-cholesterol concentrations, however, were significantly lower in the users (26 +/- 10 vs 50 +/- 13 mg.dl-1; P less than 0.05), and most of the difference was due to lower HDL2-cholesterol concentrations (6 +/- 4 vs 22 +/- 9 mg.dl-1; P less than 0.05). Postheparin plasma lipoprotein lipase activity was only slightly lower in the users (3.49 +/- 2.23 vs 5.36 +/- 1.73 mumol FFA.ml-hr-1; P= NS). but hepatic triglyceride lipase activity was significantly higher in this group (27.99 +/- 6.89 vs 11.15 +/- 2.76, mumol FFA.ml-hr-1: P less than 0.001) and correlated inversely with HDL2-cholesterol concentrations (r = -0.81; P less than 0.01). We conclude that androgenic hormones reduce HDL-cholesterol concentrations and the HDL2-cholesterol subfraction, possibly by enhancing hepatic triglyceride lipase activity.

Postheparin plasma lipolytic activities in physically active and sedentary men after varying and repeated doses of intravenous heparin

We sought to determine the optimal dose of heparin for evaluating the activities of lipoprotein lipase (LPLA) and hepatic triglyceride hydrolase (HTGLA) in postheparin plasma. Nine physically active and ten sedentary men (age 30 ± 5 yr, mean ± SD) received 30, 50, 75, and 100 IU/kg of heparin in random order during a 2-week period. Based on all the samples, the average LPLA in the athletes was 43% higher (P < 0.001) and HTGLA was 19% lower than in the untrained subjects (NS). The greatest LPLA was obtained after a heparin dose of 75 IU/kg, but LPLA after the three highest doses were not significantly different. There was also a dose effect on HTGLA (P < 0.001) with greatest activities following doses of 75 and 100 IU/kg. Despite these dose effects, subjects maintained their rank order for both postheparin lipase activities regardless of the heparin dose. The only exception was for LPLA in the sedentary men probably because of lower LPLA and a smaller range of values. We also examined the effect of repeated daily injections of 75 IU/kg heparin on LPLA, HTGLA, and serum lipids. Repeated heparin administration on three consecutive days produced no significant effects on the apparent lipase activities. When all subjects were combined, HDL-cholesterol was increased over time (P < 0.05) due to increases in both the HDL2 (P < 0.05) and HDL3-cholesterol (NS) subfractions. Infusion of heparin or saline on three consecutive days into 18 additional men, however, had no effect on any lipid parameter. We conclude that 75 IU/kg is as effective as 100 IU/kg of heparin for releasing LPLA and HTGLA and that the relative rank for lipase activities among subjects with a wide range of values is not affected by the heparin dose. Repeated heparin injections do not alter postheparin plasma lipase activities or lipid and lipoprotein concentrations measured on subsequent days.

The effects of high-carbohydrate and high-fat diets on the serum lipid and lipoprotein concentrations of endurance athletes

We examined the effects of high-carbohydrate and high-fat diets on the serum lipid levels of distance runners. For seven days before each study, subjects consumed a diet containing 15% protein, 32% fat, and 53% carbohydrate. During 14-day experimental periods, a control group (n = 10) continued the same diet while two other groups consumed 69% of their calories as either carbohydrate (n = 13) or fat (n = 14). High-density lipoprotein (HDL)-cholesterol decreased 9% during the high-carbohydrate diet because of a 26% fall in the HDL2 fraction (1.063 to 1.125 g/mL). These changes were not accompanied by changes in the levels of apolipoproteins (apo) A-I or A-II. Total and low-density lipoprotein (LDL)-cholesterol initially decreased but subsequently exceeded pre-diet values while triglyceride concentrations increased 30% to 50%. Postheparin lipoprotein lipase activity (LPLA) fell 20%. Despite these dietary effects, HDL and HDL2 cholesterol concentrations in the athletes remained above values typical of sedentary men. The high-fat diet produced different effects on the serum lipids and lipoprotein levels of the athletes. HDL levels changed little during the study although HDL-cholesterol and apo A-I on the last diet day were both slightly above initial values. The high-fat diet provided 111 g of saturated fat per day but had surprisingly little effect on total and LDL-cholesterol whereas serum triglycerides fell by 10% to 20%. Postheparin LPLA increased 30% with fat feeding and the changes in LPLA correlated with alterations in triglyceride levels (r = -0.53, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Training, Diet and Physical Characteristics of Distance Runners with Low or High Concentrations of High Density Lipoprotein Cholesterol

We examined possible determinants of serum high density lipoprotein cholesterol (HDL-C) concentrations in 56 male distance runners (aged 20-56 years) by comparing runners whose HDL-C were either above or below the group median of 63 +/- 13 (+/- SD) mg/dl. HDL-C averaged 53 +/- 7 mg/dl for runners below and 73 +/- 11 mg/dl for runners above the median. Neither exercise training (miles run per week, years of running), physical characteristics (height, weight, adiposity), or dietary factors (total daily caloric intake and daily caloric intake from protein, fat, saturated fat, polyunsaturated fat, carbohydrate, and alcohol) differed between the two groups (P greater than 0.05, MANOVA). Apo A-I (P less than 0.01) was higher and triglyceride concentrations lower (P = 0.07) in the high HDL-C group. The data were also analyzed by comparing runners in the lowest and highest tertiles for HDL-C values and essentially the same results were obtained. When all runners were combined, neither training, physical characteristics nor dietary intake was significantly related to HDL-C (P greater than 0.05). Total cholesterol and apo A-I were directly related (r = 0.35 and r = 0.66, respectively, P less than 0.01) and triglycerides inversely related (r = -0.31, P less than 0.05) to HDL-C. Plasma post-heparin lipoprotein lipase activity (LPLA), hepatic triglyceride lipase activity (HTGLA), and HDL-C subfractions were measured in 22 runners.(ABSTRACT TRUNCATED AT 250 WORDS)

POSTHEPARIN PLASMA LIPOLYTIC ACTIVITY IN PHYSICALLY ACTIVE AND SEDENTARY MEN AFTER VARYING AND REPEATED DOSES OF INTRAVENOUS HEPARIN

We sought to determine the optimal dose of heparin for evaluating the activities of lipoprotein lipase (LPLA) and hepatic triglyceride hydrolase (HTGLA) in postheparin plasma. Nine physically active and ten sedentary men (age 30 +/- 5 yr, mean +/- SD) received 30, 50, 75, and 100 IU/kg of heparin in random order during a 2-week period. Based on all the samples, the average LPLA in the athletes was 43% higher (P less than 0.001) and HTGLA was 19% lower than in the untrained subjects (NS). The greatest LPLA was obtained after a heparin dose of 75 IU/kg, but LPLA after the three highest doses were not significantly different. There was also a dose effect on HTGLA (P less than 0.001) with greatest activities following doses of 75 and 100 IU/kg. Despite these dose effects, subjects maintained their rank order for both postheparin lipase activities regardless of the heparin dose. The only exception was for LPLA in the sedentary men probably because of lower LPLA and a smaller range of values. We also examined the effect of repeated daily injections of 75 IU/kg heparin on LPLA, HTGLA, and serum lipids. Repeated heparin administration on three consecutive days produced no significant effects on the apparent lipase activities. When all subjects were combined, HDL-cholesterol was increased over time (P less than 0.05) due to increases in both the HDL2 (P less than 0.05) and HDL3-cholesterol (NS) subfractions. Infusion of heparin or saline on three consecutive days into 18 additional men, however, had no effect on any lipid parameter.(ABSTRACT TRUNCATED AT 250 WORDS)

THE EFFECTS OF HIGH CARBOHYDRATE AND HIGH FAT DIETS ON THE SERUM LIPID AND LIPOPROTEIN CONCENTRATIONS OF ENDURANCE ATHLETES

We examined the effects of high-carbohydrate and high-fat diets on the serum lipid levels of distance runners. For seven days before each study, subjects consumed a diet containing 15% protein, 32% fat, and 53% carbohydrate. During 14-day experimental periods, a control group (n = 10) continued the same diet while two other groups consumed 69% of their calories as either carbohydrate (n = 13) or fat (n = 14). High-density lipoprotein (HDL)-cholesterol decreased 9% during the high-carbohydrate diet because of a 26% fall in the HDL2 fraction (1.063 to 1.125 g/mL). These changes were not accompanied by changes in the levels of apolipoproteins (apo) A-I or A-II. Total and low-density lipoprotein (LDL)-cholesterol initially decreased but subsequently exceeded pre-diet values while triglyceride concentrations increased 30% to 50%. Postheparin lipoprotein lipase activity (LPLA) fell 20%. Despite these dietary effects, HDL and HDL2 cholesterol concentrations in the athletes remained above values typical of sedentary men. The high-fat diet produced different effects on the serum lipids and lipoprotein levels of the athletes. HDL levels changed little during the study although HDL-cholesterol and apo A-I on the last diet day were both slightly above initial values. The high-fat diet provided 111 g of saturated fat per day but had surprisingly little effect on total and LDL-cholesterol whereas serum triglycerides fell by 10% to 20%. Postheparin LPLA increased 30% with fat feeding and the changes in LPLA correlated with alterations in triglyceride levels (r = -0.53, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

2: ACUTE INCREASE IN LIPOPROTEIN LIPASE FOLLOWING PROLONGED EXERCISE

We investigated the acute effects of prolonged exercise on lipoprotein metabolism. Serum lipid and lipoprotein concentrations and plasma postheparin lipolytic activity were measured in ten well-trained men (ages 21 to 39) the day before and after a 42 km foot race. LDL cholesterol decreased by 10% (113 +/- 31 to 103 +/- 32 mg/dL, P less than 0.01) and total HDL-cholesterol levels increased by 9% (65 +/- 18 to 71 +/- 19 mg/dL, P less than 0.01) the day after the race. No changes in the concentration of apolipoprotein A-I or A-II occurred. Triglyceride levels decreased by 39% (95 +/- 38 to 58 +/- 23 mg/dL, P less than 0.001). Two days after the race, total HDL cholesterol (74 +/- 21 mg/dL, P less than 0.05) and the HDL2 subfraction (37 +/- 19 mg/dL, P less than 0.05) remained significantly elevated compared to pre-race values. Most dramatically, the level of lipoprotein lipase activity measured in postheparin plasma nearly doubled after the race, demonstrating that vigorous exercise acutely increases this enzyme activity. The increase in lipoprotein lipase activity probably mediated the fall in serum triglycerides after exercise and may also account for the increase in HDL cholesterol.