Comparative studies on the effects of propranolol and acebutolol on blood pressure, serum lipids and lipoproteins in patients with primary hypertension]

A comparative studies on the effect of propranolol and acebutolol on blood pressure, cardiac function, blood serum lipids and lipoproteins were carried out in 48 patients with the primary hypertension double-blind method was applied. Tested drugs were given for 12 weeks. It was found, that both drugs are potent and comparable hypotensive agents normalizing blood pressure in the majority of treated patients. No significant difference in the effect on heart rate and adverse reactions has been noted. Acebutolol did not change lipid metabolism parameters whereas propranolol slightly but statistically significantly increased serum triglycerides.     

Variation in tissue carnitine concentrations with age and sex in the rat

Diabetes, starvation and various hormonal treatments are known to alter drastically carnitine concentrations in the body. Before the mechanisms controlling carnitine metabolism could be determined, it was necessary to establish normal carnitine concentrations in both sexes at different ages. Carnitine was assayed in plasma, liver, heart and skeletal muscle of rats from birth to weaning. The plasma carnitine increased rapidly during the first 2 days after birth. Carnitine in both heart and skeletal muscle increased, whereas liver concentrations declined during the first week of life. A carnitine-free diet containing sufficient precursors for carnitine biosynthesis was fed to weanling rats. Groups of ten male and ten female rats were killed each week for 10 consecutive weeks. Carnitine was determined in plasma, liver, heart, skeletal muscle, urine and epididymis in the male. There was no difference in carnitine concentrations between the sexes at weaning. Plasma, heart and muscle concentrations were higher in adult male rats than in adult females. However, liver carnitine and urinary carnitine concentrations were higher in adult female than in adult male rats. The epididymal carnitine concentration increased very rapidly during 50 to 70 days of age and the differences in carnitine concentrations between the sexes also became apparent during this time. Thus both the age and the sex of the human subject or experimental animal must be considered when investigating carnitine metabolism.     

Regulation of lipid flux between liver and adipose tissue during transient hepatic steatosis in carnitine-depleted rats

Rats with carnitine deficiency due to trimethylhydrazinium propionate (mildronate) administered at 80 mg/100 g body weight per day for 10 days developed liver steatosis only upon fasting. This study aimed to determine whether the transient steatosis resulted from triglyceride accumulation due to the amount of fatty acids preserved through impaired fatty acid oxidation and/or from up-regulation of lipid exchange between liver and adipose tissue. In liver, mildronate decreased the carnitine content by approximately 13-fold and, in fasted rats, lowered the palmitate oxidation rate by 50% in the perfused organ, increased 9-fold the triglyceride content, and doubled the hepatic very low density lipoprotein secretion rate. Concomitantly, triglyceridemia was 13-fold greater than in controls. Hepatic carnitine palmitoyltransferase I activity and palmitate oxidation capacities measured in vitro were increased after treatment. Gene expression of hepatic proteins involved in fatty acid oxidation, triglyceride formation, and lipid uptake were all increased and were associated with increased hepatic free fatty acid content in treated rats. In periepididymal adipose tissue, mildronate markedly increased lipoprotein lipase and hormone-sensitive lipase activities in fed and fasted rats, respectively. On refeeding, carnitine-depleted rats exhibited a rapid decrease in blood triglycerides and free fatty acids, then after approximately 2 h, a marked drop of liver triglycerides and a progressive decrease in liver free fatty acids. Data show that up-regulation of liver activities, peripheral lipolysis, and lipoprotein lipase activity were likely essential factors for excess fat deposit and release alternately occurring in liver and adipose tissue of carnitine-depleted rats during the fed/fasted transition.     

Effect of carnitine on malondialdehyde, taurine and glutathione levels in heart of rats subjected to myocardial stress by isoproterenol

The effect of carnitine on free fatty acid, malondialdehyde, taurine and glutathione levels in myocardium was studied in rats administered isoproterenol to induce a stress in the myocardium resulting in myocardial ischaemia. Carnitine decreased the levels of free fatty acid and malondialdehyde (an index of lipid peroxidation) when compared to control rats given isoproterenol alone. Taurine and glutathione also registered a fall in the carnitine treated animals when compared to rats treated with isoproterenol alone. The results indicate that carnitine by decreasing the levels of these parameters helps the myocardium to survive from the stress induced by isoproterenol.     

Effects of 4-aminopyrazolo (3,4-d) pyrimidine on rat hepatocytes: an ultrastructural morphometric study

The prolonged administration of the hypolipidemic drug 4-aminopyrazolo (3,4-d) pyrimidine (4APP) induced conspicuous morphological changes in rat hepatocytes, which are clearly demonstrated by stereology. We observed a significant decrease in the rough endoplasmic reticulum, and an accumulation of lipid droplets, which was coupled with a comparable rise in the hepatic concentrations of total cholesterol and triglycerides. These changes were interpreted as the expression of the 4APP-provoked impairment of the synthesis of the polypeptide chains of lipoproteins and of the consequent suppression of the assembly of lipid molecules in exportable lipoproteins. We also noted a neto lowering in smooth endoplasmic reticulum and peroxisomes, a decrease which was hypothesized to be the morphological counterpart of a reduced de novo cholesterol synthesis, due to the 4APP-induced rise in the intracellular cholesterol concentration.     

Hypotensive effectiveness and metabolic effects of indapamide in patients with primary arterial hypertension

Indapamide--a non-thiazide diuretic agent--was given to 28 patients with mild and moderate hypertension in a daily dose of 2.5 mg for 12 weeks. Statistically significant decrease in both systolic and diastolic blood pressure and complete normalization of the arterial blood pressure were achieved in 82% of the treated patients. Adverse reactions were mild and transient. However, low but statistically significant decrease in blood serum potassium and changes in the carbohydrate metabolism were seen. No significant effect of the-drug on lipid metabolism was found except the low but statistically significant increase in total cholesterol. Indapamide is an efficient and well tolerated hypotensive agent. However, biochemical indices should be checked up during the treatment due to the potential adverse reactions.     

Improved methodology to assay carnitine and levels of free and total carnitine in human plasma

Carnitine, once known as vitamin Bt, is intrinsic to human tissue and is biochemically established as being acylated with fatty acids by Acyl-CoA to give Acyl-carnitines which then are transported to the inner mitochondrial membrane by a translocase. Carnitine is of increasing clinical interest and importance, and endomyocardial deficiencies of carnitine have been reported for patients in heart failure. Consequently, a reproducible and accurate analysis of human tissue specimens for levels of free carnitine and Acyl-carnitine to guide and to support continuing clinical studies of disease states is needed. We have devised an analytical method which utilizes 5,5'-dithiobis-2-nitro-benzoate and demonstrated recovery, reproducibility and precision. Hydrolysis of a specimen at 90 degrees C for 15 min, and control of pH below 6.0 are critical steps. The mean levels of free carnitine and total carnitine in 17 ordinary subjects were 50.6 +/- 9.7 nmol./ml and 62.6 +/- 11.7 nmol./ml. respectively.     

Quantification of carnitine and specific acylcarnitines by high-performance liquid chromatography: application to normal human urine and urine from patients with methylmalonic aciduria, isovaleric acidemia or medium-chain acyl-CoA dehydrogenase deficiency

This paper describes the development of a high-performance liquid chromatographic method for the quantitation of free carnitine, total carnitine, acetylcarnitine, propionylcarnitine, isovalerylcarnitine, hexanoylcarnitine and octanoylcarnitine in human urine. Carnitine and acylcarnitines were isolated from 10 or 25 μl of urine using 0.5-ml columns of silica gel, derivatized with 4'-bromophenacyl trifluoromethanesulfonate and separated by high-performance liquid chromatography. Using 4-(N,N-dimethyl-N-ethylammonio)-3-hydroxybutanoate (“e-carnitine”) as the internal standard, standard curves (10–300 nmol/ml) were generated. Carnitine and acylcarnitines were quantified (when they were present) in normal human urine and the urine of patients diagnosed with one of three different disorders of organic acid metabolism: methylmalonic aciduria, isovaleric acidemia, and medium-chain acyl-CoA dehydrogenase deficiency.     

Ozone therapy and viscosity of blood and plasma, distance of intermittent claudication and certain biochemical components in patients with diabetes type II and ischemia of the lower extremities]

Blood and plasma viscosity, total blood lipids, triglycerides, total cholesterol, free fatty acids, fibrinogen, hematocrit, and lipidogram were determined in patients with diabetes mellitus type II and coexisting symptoms of the obliterative arteriosclerosis of the lower limbs. Intermittent claudication distance has been measured parallel. The same tests have been carried out after ozone therapy. A significant improvement in the intermittent claudication and reduction in blood and plasma viscosity have been noted. There was statistically significant correlation between intermittent claudication decrease and blood viscosity reduction following ozone therapy.     

Dose and duration effects of estradiol valerate on serum and lipoprotein lipids

Non-alkylated estrogens, like estradiol valerate (F2V), are widely used in the treatment of the postmenopausal hormonal deficiency syndrome. Their effects on serum and lipoprotein lipids are characterized by an increase in the lipid constituents of high density lipoproteins (HDL) and, usually, a decrease in low density lipoproteins (LDL). These effects are considered beneficial as regards atherogenesis and the risk for cardiovascular diseases. Unlike the effects of alkylated estrogens, no concomitant increase in triglycerides (TG) in serum and very low density lipoproteins (VLDL) - adverse effects - are seen in doses of up to 2 mg E2V. In order to compare the effects of 2 and 4 mg of E2V on serum and lipoprotein lipids, 19 bilaterally oophorectomized women participated in a cross-over study after a 4 week long wash-out period. To evaluate the influence of the time factor, 10 of the women continued taking 2 mg and 9 taking 4 mg of E2V respectively for an additional period of 12 weeks, resulting in a total treatment period of 24 weeks per group. The serum lipoproteins were separated by preparative ultracentrifugation, the serum and lipoprotein lipids being assessed using commercially available kits. In the cross-over part of the study, total (TC) and free cholesterol (FC) and phospholipids (PL) increased in HDL and decreased in LDL. Neither dose increased TG in serum or VLDL. These changes in the lipoprotein pattern persisted at the end of the entire study. Consequently, within the range of commonly used doses (2 and 4 mg) E2V seems to have a constant and, in terms of cardiovascular disease, favourable influence on lipoprotein metabolism irrespective of doses and periods studied.     

Vitamine-like substances L-carnitine and acetyl-L-carnitine: from biochemical studies to medicine

Recently reported data clarify our understanding of the molecular aspects of carnitine in medicine. Carnitine is a compound necessary for the transport of acyl-CoA across the inner mitochondrial membrane for their beta-oxidation. Only L-isomer of carnitine is biologically active. The D-isomer may actually compete with L-carnitine for absorption and transport, increasing the risk of carnitine deficiency. By interaction with CoA, carnitine is involved in the intermediary metabolism by modulating free CoA pools in the cell. Detoxification properties and anabolic, antiapoptotic and neuroprotective roles of carnitine is presented. Carnitine deficiency occurs as a primary genetic defect of carnitine transport and secondary to a variety of genetic and acquired disorders. The pathophysiological states associated with carnitine deficiency have been summarized. L-Carnitine is effective for the treatment of primary and secondary carnitine deficiencies. Acetyl-L-carnitine improves cognition in the brain, significantly reversed age-associated decline in mitochondrial membrane potential and improved ambulatory activity. The therapeutic effects of carnitine and acetylcarnitine are discussed.     

Amelioration of popolysaccharide-induced sepsis in rats by free and esterified carnitine

The purpose of this study was to determine if free or esterified carnitine could alter fatty acid metabolism and ameliorate sepsis in lipopolysaccharide (LPS)-treated rats. Throughout a 96 h observation post-LPS, i.p. administration of both markedly reduced illness and accelerated recovery. Carnitine prevented the acute LPS-induced rise in serum triglycerides (45 +/- 6, 59 +/- 5 vs. 83 +/- 8 mg/ml, p < 0.001), respectively. This difference was accompanied by a significant increase in liver lipogenesis in LPS controls compared to both carnitines and normal rats (6.1 +/- 0.3 vs. 3.9 +/- 0.5, 4.3 +/- 0.5, and 1.8 +/- 0.4 mumol/h, respectively, p < 0.04). Compared to normal rats, total liver carnitine was significantly elevated in LPS controls and even higher in the carnitine groups (357 +/- 40 vs. 736 +/- 38, 796 +/- 79, and 1081 +/- 21 nmol/g). The data suggest that carnitines may be of therapeutic value in sepsis treatment and one action may be to partition fatty acids from esterification to oxidation.     

Effect of D,L-carnitine, acetyl-D,L-beta-methylcholine chloride and glycine betaine on some processes of carbohydrate metabolism of humans and goats.

Oral administration of carnitine in normal and diabetic subjects showed a marked decrease in the level of blood glucose during the oral glucose tolerance test (OGTT) except for the three hour samples in diabetic subjects, while a decrease in the level of subsequent blood pyruvate samples was observed during the OGTT in normal and diabetic subjects after the administration of carnitine. During the OGTT, the peak of blood glucose and blood pyruvate level was generally delayed in the diabetic subjects. Furthermore, the mean blood pyruvate levels were elevated above those of normal subjects during the late stages of the test. The mean levels of blood glucose and blood pyruvate of all samples after the administration of carnitine were significantly higher in diabetics than the corresponding values in noramls. Carnitine administration decreased the total blood amino acid nitrogen level only in diabetic subjects. Carnitine caused a highly significant increase in the activity of serum alanine aminotransferase in normal and diabetic subjects, while it had no effect on the activity of serum aspartate aminotransferase. In goats, the level of blood glucose during the intravenous glucose tolerance test (IVGTT) was not affected by carnitine (1,3 or 6 mg/kg body weight). Carnitine in all doses used had no effect on the total blood amino acid nitrogen during the IVGTT, or on the activity of serum alanine aminotransferase and serum aspartate aminotransferase in the fasting samples. Acetyl-D,L-beta-methylcholine had no effect on the level of blood glucose, total blood amino acid nitrogen, the activity of serum alanine aminotransferase or serum aspartate aminotransferase in normal and diabetic subjects. The level of blood pyruvate decreased both in normal and diabetic subjects, in the samples that represented the peak of the curve. Glycine betaine had no effect on blood glucose, pyruvate, total blood amino acid nitrogen and the activity of serum alanine aminotransferase or serum aspartate amino transferase in normal and diabetic subjects or in goats.     

Effect of selenium supplementation on some blood biochemical parameters in male rats

The long-term effect of selenium supplementation on blood glutathione peroxidase (GSH-Px) activity and plasma TBARS’ production (as an index of peroxidation) was evaluated in 15-mo-old male rats fed a diet supplemented with 0.25 or 0.50 ppm selenium, for 12 mo. A group of nonsupplemented age-matched rats was the control. In addition, triglycerides, phospholipids, total and free cholesterol, HDL-cholesterol, and HDL-phospholipid levels were measured in plasma. Plasma testosterone levels were also determined in order to control the aging process in these animals. The GSH-Px activity and the peroxidation level were unchanged in all the groups. However, concerning the lipid parameters, a decrease in triglycerides concentration was observed in both treated groups (p<0.05). Therefore, in these experimental conditions, despite no observed changes in parameters related to lipid peroxidation, selenium seems to be involved with triglycerides metabolism, eventually improving the triglycerides status of aged animals.     

Ethanol feeding to rats reversibly decreases hepatic carnitine palmitoyltransferase activity and increases enzyme sensitivity to malonyl-CoA

The effects of prolonged ethanol feeding on both carnitine palmitoyltransferase I activity and enzyme sensitivity to inhibition by malonyl-CoA were studied in rat liver, heart, skeletal muscle and kidney cortex mitochondria. Heart and skeletal muscle enzymes showed the highest specific activity and sensitivity to malonyl-CoA. Carnitine palmitoyltransferase I in extrahepatic tissues showed no changes on ethanol feeding. Only the liver enzyme activity was altered after long term ethanol administration, by suffering a progressive decrease in activity and a parallel increase in sensitivity to malonyl-CoA. These alterations reversed after 10 days of ethanol withdrawal. These results are discussed in relation to the control of carnitine palmitoyltransferase I and the effects of ethanol on fatty acid metabolism.     

The effect of carnitine on random-pattern flap survival in rats

Carnitine is an endogenous cofactor involved in the transport of long-chain fatty acids into the mitochondria where they undergo beta-oxidation. Through another reaction, carnitine produces free coenzyme A and reduces the ratio of acetyl-coenzyme A to coenzyme A, thereby enhancing oxidative use of glucose, augmenting adenosine triphosphate synthesis, and reducing lactate production and acidosis. Because of its regulatory action on the energy flow from the different oxidative sources, especially under ischemic conditions, carnitine has been used in cardiovascular diseases such as coronary heart disease, congestive heart failure, peripheral vascular disease, dyslipidemia, diabetes, and chronic renal diseases with satisfactory results. A flap is also a relatively ischemic tissue and may obtain benefit from carnitine. To investigate this, 30 rats were divided into three groups of 10 animals: a control group and two carnitine-treated groups. Random dorsal skin flaps were elevated on the rats. In the control group, no pharmacologic agents were used. Of the two treated groups, group 1 was treated with 50 mg/kg/day carnitine for 1 week and group 2 was treated with 100 mg/kg/day carnitine for 1 week. The areas of flap necrosis were measured in each group. The median areas of flap necrosis of the groups were 12.55, 9.23, and 4.9 cm2, respectively. There was a statistically significant improvement of flap necrosis in carnitine-treated groups compared with the control group (group 2, p = 0.001; group 3, p = 0.000). Furthermore, there was less necrosis in the high-dose carnitine-treated group than the low-dose carnitine-treated group. As a conclusion, carnitine may have a dose-dependent effect to increase flap survival in random skin flaps.     

Carnitine is associated with fatty acid metabolism in plants

The finding of acylcarnitines alongside free carnitine in Arabidopsis thaliana and other plant species, using tandem mass spectrometry coupled to liquid chromatography shows a link between carnitine and plant fatty acid metabolism. Moreover the occurrence of both medium- and long-chain acylcarnitines suggests that carnitine is connected to diverse fatty acid metabolic pathways in plant tissues. The carnitine and acylcarnitine contents in plant tissues are respectively a hundred and a thousand times lower than in animal tissues, and acylcarnitines represent less than 2% of the total carnitine pool whereas this percentage reaches 30% in animal tissues. These results suggest that carnitine plays a lesser role in lipid metabolism in plants than it does in animals.     

Animal model of systemic carnitine deficiency: analysis in C3H-H-2 degrees strain of mouse associated with juvenile visceral steatosis

We analyzed carnitine profiles in C3H-H-2 degrees strain of mouse associated with fatty liver, hyperammonemia and hypoglycemia (Koizumi et al., 1988). Carnitine levels in serum, liver and muscle of mouse with fatty liver were markedly decreased in comparison with those of control mouse (littermates without fatty liver). This is a useful animal model to analyze the role of carnitine in lipid, amino acid and carbohydrate metabolism.     

Relationships between carnitine and coenzyme A esters in tissues of normal and alloxan-diabetic sheep

1. The total acid-soluble carnitine concentrations of four tissues from Merino sheep showed a wide variation not reported for other species. The concentrations were 134, 538, 3510 and 12900nmol/g wet wt. for liver, kidney cortex, heart and skeletal muscle (M. biceps femoris) respectively. 2. The concentration of acetyl-CoA was approximately equal to the concentration of free CoA in all four tissues and the concentration of acid-soluble CoA (free CoA plus acetyl-CoA) decreased in the order liver>kidney cortex>heart>skeletal muscle. 3. The total amount of acid-soluble carnitine in skeletal muscle of lambs was 40% of that in the adult sheep, whereas the concentration of acid-soluble CoA was 2.5 times as much. A similar inverse relationship between carnitine and CoA concentrations was observed when different muscles in the adult sheep were compared. 4. Carnitine was confined to the cytosol in all four tissues examined, whereas CoA was equally distributed between the mitochondria and cytosol in liver, approx. 25% was present in the cytosol in kidney cortex and virtually none in this fraction in heart and skeletal muscle. 5. Carnitine acetyltransferase (EC 2.3.1.7) was confined to the mitochondria in all four tissues and at least 90% of the activity was latent. 6. Acetate thiokinase (EC 6.2.1.1) was predominantly (90%) present in the cytosol in liver, but less than 10% was present in this fraction in heart and skeletal muscle. 7. In alloxan-diabetes, the concentration of acetylcarnitine was increased in all four tissues examined, but the total acid-soluble carnitine concentration was increased sevenfold in the liver and twofold in kidney cortex. 8. The concentration of acetyl-CoA was approximately equal to that of free CoA in the four tissues of the alloxan diabetic sheep, but the concentration of acid-soluble CoA in liver increased approximately twofold in alloxan-diabetes. 9. The relationship between CoA and carnitine and the role of carnitine acetyltransferase in the various tissues is discussed. The quantitative importance of carnitine in ruminant metabolism is also emphasized.     

Carnitine worsens both injury and recovery of contractile function after transient ischemia in perfused rat heart

While carnitine overload appears to have therapeutic effects in pathological situations such as heart recovery after ischemia, its benefits as dietary supplementation for aerobic exercise have been questioned. We studied the effect of carnitine supplementation on the response of perfused rat heart to ischemia and reperfusion. Supplementation of the perfusion medium with 1 mM carnitine had no effect on cardiac performance in normoxic hearts, although it lowered lactate production by nearly 80%. Carnitine did not affect the amount of lactate accumulated during 30 min of ischemia, which was recovered in the perfusate immediately after reperfusion. However, carnitine worsened tissue injury, as shown by the 70% increase in creatine kinase release. Carnitine also worsened the recovery of contractile function, as revealed by the slower increase in heart rate and contractile force. In addition, carnitine supplementation increased contracture of the heart shortly after reperfusion. Therefore, in conditions where it does not increase glucose oxidation, carnitine supplementation worsens both injury and recovery of contractile function after transient ischemia in perfused rat heart.