1.
Arner, Anders, et al.
(författare)
Structural and mechanical adaptations in rat aorta in response to sustained changes in arterial pressure
1984
Ingår i: Acta Physiologica Scandinavica. - 0001-6772. ; 122:2, s. 119-126
Tidskriftsartikel (refereegranskat) abstract
Structural and mechanical adaptations in response to sustained changes in arterial pressure were studied on abdominal aorta of the male rat. Two models were used: 1. Aortic ligature (L), immediately below the renal arteries producing hypotension distal to the knot (duration before sacrifice 6 weeks or 3 months). 2. One-clip renal hypertensive rats (H) (duration 6 weeks). Normotensive sham-operated rats (C) served as controls. At sacrifice mean tail artery pressure was L: 58 +/- 1, C: 110 +/- 3, and H: 163 +/- 5 mmHg (SE, N=6). Segments of abdominal aorta were mounted in vitro for determination of their length-tension relations (activation: High-K+ solution with 2.5 mM Ca2+). At end of experiments the vessels were supramaximally stimulated at optimal circumference (1o) for active force (activation: High-K+ solution with 10 mM Ca2+, and 10(-5) M noradrenaline), and then fixated for light and electron microscopy. Passive and active length-tension relations were shifted towards lower and higher circumference values for hypo- and hypertensive vessels, respectively. The 1o values were L: 3.60 +/- 0.13, C: 4.44 +/- 0.19, and H: 4.91 +/- 0.29 mm. The media thickness at 1o was reduced in L: 56.0 +/- 3.3, and increased in H: 81.3 +/- 2.4 compared to C: 73.4 +/- 1.8 micron. Maximal active wall stress was L: 46.6 +/- 9.8, C: 74.2 +/- 7.0, and H: 83.8 +/- 7.7 mN/mm2. Intracellular volume (ICV) in the media was L: 30 +/- 2, C: 45 +/- 3, and H: 44 +/- 1% (n=4 for each).
2.
Agardh, Carl-David, et al.
(författare)
Plasma high density lipoproteins and lipolytic enzyme activities in diabetic patients
1983
Ingår i: Acta Medica Scandinavica. - 0001-6101. ; 213:2, s. 123-128
Tidskriftsartikel (refereegranskat) abstract
Eighty diabetic patients, consecutively selected from an out-patient clinic, were studied with regard to plasma lipoprotein levels, especially HDL. Patients treated with sulphonylureas had 24% lower HDL cholesterol concentrations (p less than 0.01) but only about 7% lower apo AI levels (n.s.) than those on insulin treatment. This difference could at least partly be explained by differences in age and type of diabetes. There was no relationship between the degree of diabetic control, as measured by fasting blood glucose levels, and HDL levels. In two subgroups of insulin-treated diabetics, selected to represent extremely low and high HDL levels (range 0.5-0.8 and 1.8-2.0 mmol/l, respectively) but matched with regard to age, duration of diabetes, insulin dosage and diabetic control, the activities of lipoprotein lipase and hepatic lipase in postheparin plasma were also recorded. The high HDL group had significantly higher lipoprotein lipase activities (p less than 0.01) and significantly lower hepatic lipase activities (p less than 0.05) than the low HDL group, supporting the hypothetical roles of these enzymes in HDL metabolism, and offering a tentative mechanism behind the large variability of HDL levels in diabetics.
3.
Agardh, Carl-David, et al.
(författare)
Serum beta-hexosaminidase in diabetes mellitus with reference to the type of treatment
1982
Ingår i: Acta Medica Scandinavica. - 0001-6101. ; 212:1-2, s. 39-41
Tidskriftsartikel (refereegranskat) abstract
A significantly increased serum level of beta-hexosaminidase was found in an unselected group of 85 diabetics. When the patients were divided into three groups according to type of treatment, increased enzyme levels were found only in patients treated with oral hypoglycemic agents or diet while insulin-treated patients had normal serum levels of beta-hexosaminidase. There was a positive correlation between beta-hexosaminidase and blood glucose concentration for the entire patient series. When grouped according to treatment, a positive correlation was found only in the insulin-treated group despite its normal serum activity of beta-hexosaminidase. Serum beta-hexosaminidase of patients with retinopathy did not differ from the mean value of their group. It is concluded that the activity of beta-hexosaminidase in diabetics can produce different results depending on the type of patients under study.
4.
Hansson, P, et al.
(författare)
Experimental hyperthyroidism in man: effects on plasma lipoproteins, lipoprotein lipase and hepatic lipase
1983
Ingår i: Hormone and Metabolic Research. - 1439-4286. ; 15:9, s. 449-452
Tidskriftsartikel (refereegranskat) abstract
We have studied the effects of triiodothyronine administration (20-40 micrograms three times daily over one week) in six healthy young men, on the activities of lipoprotein lipase and hepatic lipase and on plasma lipoprotein concentrations. Hepatic lipase activity in post-heparin plasma rose by 46 +/- 25% (p less than 0.025), whereas the activity of lipoprotein lipase did not change significantly. Plasma cholesterol concentrations decreased by about 20% (p less than 0.025), whereas there was no change in plasma triglyceride levels. The fall in plasma cholesterol could be accounted for by a reduction of HDL cholesterol (-11%, p less than 0.025) as well as LDL cholesterol (-27%, p less than 0.025). The data emphasize the role of hepatic lipase in the lipoprotein alterations associated with thyroid dysfunction.
5.
Mulvany, M J, et al.
(författare)
Potentiating and depressive effects of ouabain and potassium-free solutions on rat mesenteric resistance vessels.
1982
Ingår i: Circulation research. - 0009-7330. ; 51:4, s. 514-24
Tidskriftsartikel (refereegranskat) abstract
We have investigated the in vitro effects of ouabain and K-free solutions on some pharmacological and electrophysiological properties of rat mesenteric resistance vessels (internal diameter approximately 190 micrometers). Vessels were mounted as ring preparations on a myograph capable of measuring their isometric wall tension. In normal saline solutions, vessels did not exhibit any tone and had a membrane potential of -54 mV. Both 1 mM ouabain and K-free solutions caused a transient depolarization of 5-8 mV; thereafter the membrane slowly depolarized to about -45 mV after 30 minutes. There was no mechanical response to ouabain, but K-free solutions caused a transient development of tension which could be inhibited by phentolamine (1 microM). In norepinephrine-activated vessels, exposure to ouabain or K-free solutions caused a small depolarization and an increase in tension. Long-term (30-minute) exposure to 1 mM ouabain or K-free solutions reduced the amplitude of norepinephrine responses and, for the lower (but not the higher) norepinephrine concentrations, the membranes were about 14 mV more depolarized than control. The mechanical responses to a cocktail of norepinephrine in a high potassium solution were, however, unaffected. Re-exposure to normal saline solution produced a transient hyperpolarization and transiently eliminated the norepinephrine response, but thereafter the membrane potential and response returned to normal. The results indicate that ouabain and K-free solutions can have both short-term potentiating and long-term depressive effects on the mechanical response of rat mesenteric resistance vessels to norepinephrine.
6.
7.
Sorbris, Ralph, et al.
(författare)
Effects of weight reduction on plasma lipoproteins and adipose tissue metabolism in obese subjects
1981
Ingår i: European Journal of Clinical Investigation. - : Wiley. - 0014-2972 .- 1365-2362. ; 11:6, s. 491-500
Tidskriftsartikel (refereegranskat) abstract
The relationship between obesity and alterations in adipose tissue metabolism and lipid transport was studied in fourteen obese subjects before and after a weight reduction of 4-22 kg. Blood glucose and plasma insulin patterns after peroral glucose intake improved significantly, and plasma glucagon levels decreased markedly after treatment. Plasma triglyceride and total cholesterol levels were not altered, but there was a 20% (P less than 0.05) increase in HDL concentrations. Plasma free fatty acid and glycerol concentrations decreased, in parallel to a decrease in lipolysis rate in vitro. Lipoprotein lipase and hepatic lipase activities in postheparin plasma, as well as the intravenous fat tolerance test, were normal and did not change significantly after weight loss. Lipoprotein lipase activity in adipose tissue, expressed per cell, was elevated and did not change after weight reduction. Also, the enzyme activity did not increase after glucose intake before or after treatment. The lack of effect on lipoprotein lipase activity and regulation in combination with significant improvements of other aspects of lipid and glucose transport is consistent with the view that alterations in LPL activity and regulation may represent an early and possibly primary defect in the development of obesity.
8.
Stubbe, Ingo, et al.
(författare)
High-density lipoprotein concentrations increase after stopping smoking
1982
Ingår i: British Medical Journal (Clinical Research Edition). - 0267-0623. ; 284:6328, s. 1511-1513
Tidskriftsartikel (refereegranskat) abstract
Concentrations of plasma lipoproteins in 10 men who were habitual smokers were monitored for six weeks after they stopped smoking and related to changes in diet and body weight. The energy intake increased by 10% (p less than 0.05) owing to a higher consumption of carbohydrates and fat, and body weight increased by 2% (p less than 0.01). Plasma triglyceride, cholesterol, and low-density lipoprotein cholesterol concentrations did not change significantly. The most prominent finding was a rapid and pronounced increased in high-density lipoprotein concentrations. From comparatively low values (mean 0.82 mmol/1) they rose by 29% (p less than 0.01) within two weeks and remained at this value throughout the observation period. In three subjects who resumed smoking after the end of the study they again fell to initial values six weeks later. The initial increase in concentration could be accounted for mainly by an increase in the esterified fraction and only to a lesser extent in the free cholesterol fraction. The changes in concentrations were accompanied by similar but less pronounced rises in high-density lipoprotein phospholipid and in apolipoprotein AI concentrations (p less than 0.01), whereas high-density lipoprotein phospholipid and in apolipoprotein AI concentration (p less than 0.01), whereas high-density lipoprotein triglyceride concentrations did not change significantly. These findings confirm and extend those of earlier cross-sectional studies which showed low concentrations of high-density lipoproteins in cigarette smokers, A significant correlation between the rise in high-density lipoprotein cholesterol concentrations and the increase in fat consumption after stopping smoking indicate that the changes in high-density lipoprotein concentrations may be partly due to nutritional factors.
9.
Valdemarsson, Stig, et al.
(författare)
Relations between thyroid function, hepatic and lipoprotein lipase activities, and plasma lipoprotein concentrations
1983
Ingår i: Acta Endocrinologica. - 0001-5598. ; 104:1, s. 50-56
Tidskriftsartikel (refereegranskat) abstract
Lipoprotein concentrations and activities of lipoprotein lipase (LPL) and hepatic lipase (HL) were measured in 70 subjects with thyroid function ranging from overt hypothyroidism over subclinical hypothyroidism and euthyroidism to hyperthyroidism. In parallel with serum T3 (S-T3) concentrations increasing from low in hypothyroidism to high in hyperthyroidism there were gradually higher HL activities over the full spectrum of thyroid function, accompanied by decreasing levels of total and low density lipoprotein (LDL) cholesterol. High density lipoprotein (HDL) cholesterol was lower (P less than 0.05) in hyperthyroidism than in euthyroidism but not significantly changed in the hypothyroid groups. HL was correlated to S-T3 (r = 0.77, P less than 0.001), LDL cholesterol to log S-T3 (r = -0.76, P less than 0.001), and LDL cholesterol to log HL (r = -0.55, P less than 0.001). The activity of LPL was decreased (P less than 0.001) in overt hypothyroidism compared to euthyroidism but, in contrast to HL, the activity of LPL was not increased in hyperthyroidism. The plasma triglyceride (P-TG) concentration was elevated (P less than 0.01) in overt hypothyroidism but not significantly changed in subclinical hypothyroidism or in hyperthyroidism. The LPL activity was correlated to log S-T3 (r = 0.45, P less than 0.001), P-TG to log S-T3 (r = -0.37, P less than 0.01) and P-TG to log LPL activity (r = -0.71, P less than 0.001). Our results demonstrate that thyroid hormones influence HL and LPL activities in different ways, suggesting different mechanisms of action. Changes in HL activity seem to be an important mechanism for the disturbance of cholesterol metabolism in thyroid dysfunction while the thyroid hormone influence on LPL seems to be of importance mainly for the disturbance in triglyceride metabolism.
10.
Valdemarsson, Stig, et al.
(författare)
Treatment of hyperthyroidism: effects on hepatic lipase, lipoprotein lipase, LCAT and plasma lipoproteins
1984
Ingår i: Scandinavian Journal of Clinical & Laboratory Investigation. - : Informa UK Limited. - 1502-7686 .- 0036-5513. ; 44:3, s. 183-189
Tidskriftsartikel (refereegranskat) abstract
The activities of hepatic lipase and of lipoprotein lipase, the elimination rate of exogenous triglyceride and the cholesterol esterification rate were determined and related to plasma lipoprotein concentrations in 16 patients before and after treatment for hyperthyroidism. The activity of hepatic lipase was significantly higher (65%) before than after treatment, while the activity of lipoprotein lipase and the elimination rate of exogenous triglyceride remained unchanged. The endogenous cholesterol esterifying ability decreased after treatment, whereas no change occurred in the fractional cholesterol esterification rate measured with normal plasma as substrate. The concentrations of LDL-cholesterol and HDL-cholesterol increased significantly after treatment. The decrease in hepatic lipase activities was correlated to the decrease in S-T3 concentrations (r = 0.77, P less than 0.001) and to the increase in HDL-cholesterol concentrations (r = 0.51, P less than 0.05). The activities of lipoprotein lipase were positively correlated to the concentrations of HDL-cholesterol both before (r = 0.54, P less than 0.05) and after (r = 0.59, P less than 0.05) treatment. These results support the view that hepatic lipase and lipoprotein lipase are both important determinants of plasma HDL concentrations and suggest that an increased hepatic lipase activity contributes to the lower HDL levels in hyperthyroid patients.
