Adipose Tissue In Dogs Research Articles

Subcutaneous adipose tissue blood flow and triacylglycerol-mobilization during prolonged exercise in dogs

In 6 dogs concentration differences for glycerol and FFA were measured between the aorta and the external pudendal vein, a vein which mainly drains subcutaneous adipose tissue in dogs, during prolonged exercise. It was found that the a-v differences increased about 2-fold for both glycerol and FFA, however great interindividual differences were found. In 4 dogs adipose tissue blood flow, glycerol and FFA a-v differences were measured simultaneously, and the mobilizations of glycerol and FFA as well as the re-esterification of FFA were calculated. After 2 h of exercise the values were in the range of 1-7 umol/(100 g.min) for FFA and glycerol mobilizations while the FFA re-esterification was in the range of 2-14 umol/(100 g.min). It was found that the FFA/albumin ratio in adipose venous blood, on average 3.6 was at a level at which the FFA mobilization has been shown to depend on the adipose tissue blood flow in isolated fat pads. In 11 dogs subcutaneous adipose tissue blood flow rose 2-fold during exercise from about 5-10 ml/(100 g.min). It is concluded that the subcutaneous adipose tissue blood flow response to exercise is equal in man and dog, that lipolysis, FFA mobilization and FFA re-esterification are increased in subcutaneous adipose tissue during exercise, and that the increase in blood flows is of importance for the enhanced FFA mobilization during exercise.

Antilipolytic Effect of Adenosine in Dog Adipose Tissue in Situ

Antilipolytic Effect of Adenosine in Dog Adipose Tissue in Situ

Release of Adenosine‐like Material from Isolated Perfused Dog Adipose Tissue Following Sympathetic Nerve Stimulation and its Inhibition by Adrenergic α‐Receptor Blockade

Following the intraarterial infusion of 3H-adenine to isolated perfused canine subcutaneous adipose tissue, its adenine nucleotides are labelled. A continuous release of radioactivity, comprised of non-nucleotide material, was observed. The rate of this release was markedly enhanced by sympathetic nerve stimulation. The major components of the enhanced release appeared to be inosine and adenosine. Adrenergic alpha-receptor blockade (phentolamine or Hydergin) abolished the enhanced nucleoside release, while glycerol release was enhanced. The release of radioactivity was decreased during mechanical blood flow reduction and enhanced afterwards. However, the magnitude of this enhancement of release after clamp was much less than following nerve stimulation. The results suggest that adenosine or a closely related compound is released from canine subcutaneous adipose tissue by sympathetic nerve stimulation and that the release is related to adrenergic alpha-receptor stimulation. Since adenosine is a potent inhibitor of catecholamine induced lipolysis in this tissue the possibility of a regulatory role must be considered.

Disappearance of 133Xenon and 125Iodide and extraction of 86Rubidium in subcutaneous adipose tissue during sympathetic nerve stimulation.

AbstractEffects of sympathetic nerve stimulation on the disappearance rates of 133Xenon and 125Iodide from a local depot as well as on the extraction of 86Rubidium from blood have been studied in the subcutaneous adipose tissue of dogs during constant blood flow perfusion. Resting mean k‐values for 133Xenon were 0.0040 min‐1(n = 10) and for 125Iodide 0.0386 min‐1(n = 5) while the PS‐products for 86Rubidium had a mean value of 2.5 ml × min‐1X 100 g‐1(n = 17). During sympathetic nerve stimulation a frequency dependent decrease of disappearance rates and PS‐products was found. The latter were reduced by an average of 30 % while the reductions of the disappearance rates were twice as large and similar for 133Xenon and 125Iodide. These results suggest a decrease in the perfused capillary surface area during sympathetic nerve stimulation.

Uptake and metabolism of adenosine by human erythrocyte ghosts.

Uptake and metabolism of adenosine by human erythrocyte ghosts.

Some characteristics of lipolysis in dog adipose tissue. Effects of noradrenaline, prostaglandin E1 and nicotinic acid.

AbstractOmental adipose tissue from twelwe fasted dogs of both sexes was incubated in vitro and the glycerol release determined as a measure of lipolysis. The effect of addition of noradrenaline, prostaglandin E1 (PGE1) and nicotinic acid into the medium was studied. On basal lipolysis the following effects were obtained with PGE., 0.1 μg PGE Inhibition 4 dogs, no effect 6 dogs. 1 μg PGE1: Inhibition 1 dog, no effect 5 dogs, stimulation 6 dogs, 10 pg PGE1: Inhibition 1 dog, no effect 3 dogs, stimulation 8 dogs. A dualistic action of PGE1 was seen in some of the dogs. PGE1, 1 μg, inhibited lipolysis stimulated by noradrenaline only in those dogs where the same amount of PGE1 either inhibited or did not modify basal lipolysis. In those dogs where 1 μg of PGE1 stimulated basal lipolysis, this dose did not inhibit the stimulation caused by noradrenaline. The β‐adrenergic blocker Kö 592 inhibited the stimulation of lipolysis caused by PGE, only slightly while Kö 592 completely inhibited the stimulation elicited by noradrenaline.Nicotinic acid inhibited the basal lipolysis in five of ten dogs and the stimulation induced by noradrenaline in three of ten. In those dogs where nicotinic acid inhibited lipolysis PGE1 was in general also inhibitory.

Triglyceride sub‐classes of various dog adipose tissue sites

Lipids were extracted from four dog adipose tissue sites, perirenal, pericardial, inguinal subcutaneous, and mesenteric. The triglycerides were purified by thin-layer chromatography and the sub-classes separated by silver nitrate-silica gel plates. Gas chromatography was used to delineate the fatty acid composition of each subclass. The major sub-class was 011, followed by 012, 001, 111 and 112 in that order (0=saturated fatty acid; 1=one double bond; 2=two double bonds). The other components were present in minor amounts. The pericardial triglyceride had more 012 while the perirenal adipose tissue contained less 011 and more 001 than other sites. The other sub-classes were essentially similar.The distribution, based on 100%, of each saturated fatty acid was not the same in all sub-classes, although the over-all average was similar in each site.

Quantitative and qualitative lipid correlation in experimental endogenous hyperlipemia

The reversible endogenous hyperlipemia in dogs, elicited by the detergent Triton which was given intravenously, was used to study the interrelations of serum lipids. In the cholesterol ester fraction an increase occurs in both monounsaturated and in saturated fatty acids, excepting myristic; while a decrease occurs in polyunsaturated fatty acids. The fatty acids of cholesterol esters of normal dogs contain 22% oleic acid, and only 24% when serum lipids are increased to almost double their normal value (TC=400-500 mg/100 ml). However there is a critical level above which a rapid rise in oleic acid occurs and, in severe hyperlipemia (TC=1500 +/-430 mg/100 ml), this acid constitutes almost half of the esterified fatty acid component.Since there is no evidence that Triton directly regulates fatty acid synthesis, the lipid fraction-fatty acid interrelationship may be secondary to lipid mobilization from endogenous sources. This concept is supported by the fact that the increased serum fatty acids are only those which can be synthesized by animals. It is suggested, on the basis of a marked increased of endogenously produced fatty acids, that, at critical lipid levels, shortage of polyunsaturated fatty acids from exogenous sources occurs. This might be of sufficient degree to accelerate fatty acid synthesis to meet the need for fatty acids for energy requirements. There may also be need of fatty acid for esterification of chiefly the accumulated free cholesterol split from lipoprotein by Triton.Triton-induced changes in cholesterol ester fatty acids result in patterns which closely resemble those in the adipose tissue of dog and man and in the serum of human endogenous hyperlipemia.

Lactate dehydrogenase activity in dog adipose tissue.

SummaryWithin the same animal, LDH activity is significantly higher in the peri-cardial than in the inguinal adipose tssue. This is related to the flavoprotein content of the two tissues. High pyruvate concentrations inhibit LDH activity from either source to the same extent. The degree of inhibition by urea is always significantly less (p<.005) at the high (1 × 10−2 M) than at the low (5 × 10−4 M) pyruvate level. Oxalate inhibits inguinal adipose tissue LDH less at the high than at the low pyruvate level, while showing a reverse effect on the enzyme from peri-cardial tissue. Michaelis-Menten constants (KM) for pyruvate were calculated from activities both in the absence and in the presence of urea and oxalate. KM values were significantly decreased in the presence of 2.0 M urea. All levels of oxalate studied increased the KM of pericardial adipose tissue LDH, but did not affect that of the inguinal adipose tissue enzyme. Incubation at 59°C for 10 minutes inactivates both enzymes to about the same extent,...

Nervous Regulation of Blood Flow in the Subcutaneous Adipose Tissue in Dogs

AbstractThe subcutaneous adipose tissue in the lower abdominal region between the pubis and the pubic mammary gland was isolated from fascia and skin and prepared for direct measurement of the blood flow. Resting blood flow varied between 3 and 19ml/min ˙ 100g adipose tissue (mean 8.5ml/min ˙ 100g; n = 17). Stimulation of the nerve supplying the adipose tissue or of the sympathetic trunk induced a stimulus‐frequency related vasoconstriction which was abolished by agents with α‐receptor blocking properties. Following α‐receptor blockade the same nerve stimulation increased the blood flow to a maximum of about 25ml/min ˙ 100g. The degree of vasodilatation was also related to the stimulus frequency. Propranolol, a β‐receptor blocking agent, abolished the vasodilator response. Reflex adjustment of the peripheral vasomotor tonus upon carotid artery occlusion and activation of the sympathetic cholinergic vasodilator nerves in the hypothalamus did not appreciably change the vascular resistance in the adipose tissue.

Release of free fatty acids from subcutaneous adipose tissue in dogs following sympathetic nerve stimulation.

AbstractA technique suitable for quantitative measurements of circulatory and metabolic processes in subcutaneous adipose tissue in vivo is described. Electrical stimulation of sympathetic nerves to the adipose tissue induces a net release of FFA as well as vasoconstriction. A maximal release rate of FFA seems to be obtained with a stimulus frequency of about 3/sec. The vasoconstrictor reaction following sympathetic nerve stimulation supresses the release rate of FFA. This is especially true following stimulation with higher frequencies of 5/sec, or more. Provided the stimulation frequencies are within the physiological range the stimulation period must be 2 min, or more, in order to produce a rise in the release rate of FFA. The data indicate that sympathetic nerves to subcutaneous adipose tissue have the ability to mobilize energy for the organism within a few minutes.

Studies on the toxicity and metabolism of β-apo-8′-carotenal in dogs

Dogs tolerated daily administration of 1000 mg and 100mg of β-apo-8′-carotenal for 14 weeks without the occurrence of toxic manifestations; general health, blood counts, liver and kidney function tests remained within normal limits. In terms of vitamin A activity, these doses are equivalent to 1,166,900 IU and 116,690 IU. Gross and microscopic findings were not unusual except for some deposition of yellow pigment in mesenteric and perirenal adipose tissue of dogs treated with 1000 mg of apocarotenal; on occasion, some pigment was also found in the renal cortex, adrenals, and liver of these animals. Plasma vitamin A levels were not elevated despite the prolonged treatment interval; levels of apocarotenal in plasma were significantly increased in dogs given 1000 mg of this carotenoid. Assays of the tissues showed the kidneys of treated animals to contain three- to fivefold higher amounts of vitamin A than controls; apocarotenal concentrations also tended to be elevated in dogs administered this carotenoid orally. Metabolites found in the urine of dogs repeatedly administered this carotenoid include, in addition to β-apo-8′-carotenal, free and esterified vitamin A and β-8′-apocarotenoic acid.