Regulation of myocardial lipoprotein lipase activity by diabetes and thyroid hormones

1994 ◽  
Vol 72 (11) ◽  
pp. 1259-1264 ◽  
Author(s):  
Limin Liu ◽  
David L. Severson
Keyword(s):  
Thyroid Hormones ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Hormone Treatment ◽  
Diabetic Rats ◽  
Lipoprotein Lipase Activity ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Perfused Hearts

Administration of streptozotocin (100 mg/kg) to adult Sprague–Dawley rats reduced both functional (heparin releasable) lipoprotein lipase activity in perfused hearts and total and heparin-releasable lipoprotein lipase activity in isolated cardio-myocytes, and produced a hypothyroid state (decreased plasma levels of triiodothyronine and thyroxine). Administration of replacement doses of triiodothyronine (3 or 10 μg/kg for 3 days) to diabetic rats normalized heparin-releasable lipoprotein lipase activity in perfused hearts, but the depressed lipoprotein lipase activity in cardiomyocytes from diabetic hearts was unchanged by in vivo thyroid hormone treatment. However, hypothyroidism in thyroidectomized rats did not alter lipoprotein lipase activity in either perfused hearts or isolated cardiomyocytes. Therefore, thyroid hormones may interact with some other factor(s) in this acute, insulin-deficient model of diabetes to selectively regulate functional, heparin-releasable lipoprotein lipase activity in perfused hearts.Key words: diabetes, hypothyroidism, lipoprotein lipase, perfused hearts, cardiomyocytes.

Acute diabetes does not reduce heparin-releasable lipoprotein lipase activity in perfused hearts from Wistar–Kyoto rats

1993 ◽  
Vol 71 (9) ◽  
pp. 657-661 ◽  
Author(s):  
Brian Rodrigues ◽  
David L. Severson
Keyword(s):  
Lipoprotein Lipase ◽  
Cardiac Myocytes ◽  
Lipase Activity ◽  
Cardiac Myocyte ◽  
Plasma Concentrations ◽  
Lipoprotein Lipase Activity ◽  
Sprague Dawley ◽  
Wistar Kyoto Rats ◽  
Wistar Kyoto ◽  
Perfused Hearts

The induction of diabetes (3–5 days duration) in Wistar–Kyoto rats by the administration of streptozotocin (100 mg/kg) did not increase plasma concentrations of triacylglycerols or free fatty acids, and did not reduce heparin-releasable (functional) lipoprotein lipase activity in perfused hearts. By comparison, diabetic Sprague–Dawley rats were characterized as having hypertriglyceridemia and decreased heparin-releasable lipoprotein lipase activity in perfused hearts. Therefore, the diabetes-induced reduction in myocardial lipoprotein lipase activity in Sprague–Dawley rat hearts may, at least in part, be a compensatory response to the hypertriglyceridemia and increased fatty acid delivery to the myocardial cell, which is a characteristic feature of most severe, insulin-deficient models of diabetes mellitus. Although functional, endothelium-bound lipoprotein lipase activity was not reduced in diabetic perfused hearts from Wistar–Kyoto rats, cellular and heparin-releasable lipoprotein lipase activity was reduced in cardiac myocyte preparations, suggesting that other mechanisms in addition to plasma triacylglycerol must regulate lipoprotein lipase activity in the whole diabetic Wistar–Kyoto rat heart and that cardiac myocytes may not be the exclusive source of functional lipoprotein lipase in the diabetic myocardium.Key words: diabetes, hypertriglyceridemia, lipoprotein lipase, perfused hearts, cardiac myocytes.

Lipoprotein lipase-suppressing mediator in serum of endotoxin-treated rats

1986 ◽  
Vol 251 (4) ◽  
pp. E470-E476 ◽  
Author(s):  
G. J. Bagby ◽  
C. B. Corll ◽  
J. J. Thompson ◽  
L. A. Wilson
Keyword(s):  
Lipoprotein Lipase ◽  
Exposure Time ◽  
Lipase Activity ◽  
Significant Suppression ◽  
Lipoprotein Lipase Activity ◽  
Activity Maximum ◽  
A Cell

The conditions under which lipoprotein lipase-suppressing mediator is present in serum of endotoxin-treated rats was determined in this study. The suppression of lipoprotein lipase activity in 3T3-L1 cells was used as a bioassay for mediator in serum. Endotoxin (0.1-10 micrograms/ml) and serum from control rats did not suppress lipoprotein lipase activity. Maximum suppression of cell lipoprotein lipase activity (70%) by serum from endotoxic rats required a cell exposure time of 5 h. At the highest dose of endotoxin used (1 mg/100 g), significant suppression was achieved when cells were incubated with 0.5% serum from endotoxic rats (P less than 0.05). Serum obtained 2-3 h after endotoxin injection possessed the maximal ability to suppress lipase activity, but suppressing activity was not present in serum collected 8 h after endotoxin. Rats rendered tolerant to endotoxin by 5 daily injections (0.1 mg/100 g) did not contain detectable levels of mediator in serum after endotoxin injection. The results demonstrate that the presence of lipoprotein lipase activity-suppressing mediator is transitory after in vivo exposure of naive rats to endotoxin, but does not appear in serum of endotoxin tolerant rats.

Regulation of lipoprotein lipase activity in cardiac myocytes from control and diabetic rat hearts by plasma lipids

1992 ◽  
Vol 70 (9) ◽  
pp. 1271-1279 ◽  
Author(s):  
Brian Rodrigues ◽  
Janice E. A. Braun ◽  
Michael Spooner ◽  
David L. Severson
Keyword(s):  
Lipoprotein Lipase ◽  
Cardiac Myocytes ◽  
Lipase Activity ◽  
Plasma Lipids ◽  
Inhibitory Effect ◽  
Diabetic Rats ◽  
Diabetic Rat ◽  
Lipoprotein Lipase Activity ◽  
Triton Wr 1339 ◽  
Plasma Triacylglycerol

The objective of this investigation was to test the hypothesis that the diabetes-induced reduction in lipoprotein lipase activity in cardiac myocytes may be due to hypertriglyceridemia. Administration of 4-aminopyrazolopyrimidine (50 mg/kg) to control rats for 24 h reduced plasma triacylglycerol levels and increased the heparin-induced release of lipoprotein lipase into the incubation medium of cardiac myocytes. The acute (3–5 days) induction of diabetes by streptozotocin (100 mg/kg) produced hypertriglyceridemia and reduced heparin-releasable lipoprotein lipase activity in cardiac myocytes. Treatment of diabetic rats with 4-aminopyrazolopyrimidine resulted in a fall in plasma triacylglycerol content and increased heparin-releasable lipoprotein lipase activity. Administration of Triton WR-1339 also resulted in hypertriglyceridemia, but the heparin-induced release of lipoprotein lipase from control cardiac myocytes was not reduced in the absence of lipolysis of triacylglycerol-rich lipoproteins. Treatment with Triton WR-1339 did, however, increase the heparin-induced release of lipoprotein lipase from diabetic cardiac myocytes. Preparation of cardiac myocytes with 0.9 mM oleic acid resulted in a decrease in both total cellular and heparin-releasable lipoprotein lipase activities. These results suggest that the diabetes-induced reduction in heart lipoprotein lipase activity may, at least in part, be due to an inhibitory effect of free fatty acids, derived either from lipoprotein degradation or from adipose tissue lipolysis, on lipoprotein lipase activity in (and (or) release from) cardiac myocytes.Key words: diabetes, plasma triacylglycerols, cardiac myocytes, lipoprotein lipase.

Oscillatory changes in muscle lipoprotein lipase activity of fed and starved rats.

1977 ◽  
Vol 233 (4) ◽  
pp. E316
Author(s):  
T J Kotlar ◽  
J Borensztajn
Keyword(s):  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Feeding Habits ◽  
Quadriceps Muscle ◽  
Diabetic Rats ◽  
Lipoprotein Lipase Activity ◽  
Nocturnal Feeding ◽  
Ad Libitum ◽  
Short Time ◽  
Fast Twitch

Lipoprotein lipase activity was measured at short time intervals in cardiac and skeletal muscles of normal and streptozotocin-treated diabetic rats fed ad libitum or deprived of food. In normal animals fed ad libitum, lipoprotein lipase activities of heart, diaphragm, soleus, and fast-twitch red fibers of the quadriceps muscle showed rhythmic oscillations that appeared to coincide with the nocturnal feeding habits of the animals. During the day (7 A.M. to 7 P.M.), when food consumption by the rats was greatly reduced, lipoprotein lipase activity in all muscles increased, followed by a decline to basal levels during the night. Similar oscillatory changes in lipoprotein lipase activity were observed in the muscles of diabetic rats fed ad libitum. In normal rats deprived of food, however, the oscillatory changes in muscle lipoprotein lipase activity were not abolished and persisted for at least 48 h. In diabetic rats starved during a 48-h period, the oscillatory changes in muscle lipoprotein lipase activity were markedly altered. In all animals, muscle lipoprotein lipase activities were not correlated to plasma glucagon levels.

scholarly journals Injury to the Endothelial Surface Layer Induces Glomerular Hyperfiltration Rats with Early-Stage Diabetes

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Chunyang Zhang ◽  
Yao Meng ◽  
Qi Liu ◽  
Miao Xuan ◽  
Lanyu Zhang ◽  
...  
Keyword(s):  
Surface Layer ◽  
Particle Density ◽  
Early Stage ◽  
Diabetic Rats ◽  
Mesangial Matrix ◽  
Sprague Dawley ◽  
Endothelial Surface Layer ◽  
Sprague Dawley Rats ◽  
Endothelial Surface

Glomerular endothelial surface layer (ESL) may play a role in the mechanisms of albuminuria in diabetic nephropathy, which lack evidencein vivo. The effects of high glucose on the passage of albumin across the glomerular ESL were analysed in streptozotocin-induced diabetic Sprague-Dawley rats for 4 weeks. Albuminuria and glomerular mesangial matrix were significantly increased in diabetic rats. The passage of albumin across the ESL, as measured by albumin-colloid gold particle density in the glomerular basement membrane (GBM), was increased significantly in diabetic rats. The thickness of the glomerular ESL, examined indirectly by infusing Intralipid into vessels using an electron microscope, was significantly decreased and the GBM exhibited little change in diabetic rats. In summary, the glomerular ESL may play a role in the pathogenesis of albuminuria in rats with early-stage diabetes.

scholarly journals The inhibition in vivo of lipoprotein lipase (clearing-factor lipase) activity by triton WR-1339

1976 ◽  
Vol 156 (3) ◽  
pp. 539-543 ◽  
Author(s):  
J Borensztajn ◽  
M S Rone ◽  
T J Kotlar
Keyword(s):  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Lipoprotein Lipase Activity ◽  
Rat Hearts ◽  
Maximum Inhibition ◽  
Triton Wr 1339 ◽  
Perfused Rat Hearts ◽  
Hydrolysis Of ◽  
Isolated Perfused Rat Hearts

1. Lipoprotein lipase activity was measured in heart homogenates and in heparin-releasable and non-releasable fractions of isolated perfused rat hearts, after the intravenous injection of Triton WR-1339. 2. In homogenates of hearts from starved, rats, lipoprotein lipase activity was significantly inhibited (P less than 0.001) 2h after the injection of Triton. This inhibition was restricted exclusively to the heparin-releasable fraction. Maximum inhibition occurred 30 min after the injection and corresponded to about 60% of the lipoprotein lipase activity that could be released from the heart during 30 s perfusion with heparin. 3. Hearts of Triton-treated starved rats were unable to take up and utilize 14C-labelled chylomicron triacylglycerol fatty acids, even though about 40% of heparin-releasable activity remained in the hearts. 4. It is concluded that Triton selectively inhibits the functional lipoprotein lipase, i.e. the enzyme directly involved in the hydrolysis of circulating plasma triacylglycerols. 5. Lipoprotein lipase activities measured in homogenates of soleus muscle of starved rats and adipose tissue of fed rats were decreased by 25 and 39% respectively after Triton injection. It is concluded that, by analogy with the heart, these Triton-inhibitable activities correspond to the functional lipoprotein lipase.

Sign in / Sign up

Export Citation Format

Share Document