Effects of vasoactive drugs on circulation in canine subcutaneous adipose tissue.
TL;DR: PGE1 produced clearcut vasodilatations at calculated blood concentrations as low as 10-9M and was found to be the most potent of the drugs tested and discussed that the pronounced CFC increase during sympathetic nerve stimulation is due to an increased permeability of the capillary membrane.
Abstract: The circulatory effects of acetylcholine, bradykinin, isoprenaline, histamine, 5-hydroxytrypt-amine (5-HT), noradrenaline and prostaglandin Ei (PGE1) were studied in the canine subcutaneous adipose tissue. PGE1 produced clearcut vasodilatations at calculated blood concentrations as low as 10-9M and was found to be the most potent of the drugs tested. PGE1 was about 1000 times more potent than acetylcholine and about 10 times more potent than histamine. 5-HT induced a moderate blood flow increase with no change or a decrease of tissue volume, indicating a constriction of the venous section. The vascular responses to noradrenaline infusions were essentially similar to those produced by sympathetic nerve activation, i.e. constriction of arterioles and veins and a markedly increased capillary filtration coefficient (CFC). Histamine and bradykinin induced increases of CFC of the same magnitude as did sympathetic nerve stimulation, whereas acetylcholine, isoprenaline, 5-HT and PGE1 induced smaller increases of CFC. Sympathetic nerve stimulation superimposed upon infusions of the latter drugs produced a further marked increase of CFC, while nerve stimulation applied during a period of histamine or bradykinin infusion produced no further rise or even a decrease of CFC. It is discussed that the pronounced CFC increase during sympathetic nerve stimulation is due to an increased permeability of the capillary membrane.
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TL;DR: It is hypothesize that the SNS innervation of WAT is an important contributor to the apparent "regulation" of total body fat.
Abstract: We review the extensive physiological and neuroanatomical evidence for the innervation of white adipose tissue (WAT) by the sympathetic nervous system (SNS) as well as what is known about the sensory innervation of this tissue. The SNS innervation of WAT appears to be a part of the general SNS outflow from the central nervous system, consisting of structures and connections throughout the neural axis. The innervation of WAT by the SNS could play a role in the regulation of total body fat in general, most likely plays an important role in regional differences in lipid mobilization specifically, and may have a trophic affect on WAT. The exact nature of the SNS innervation of WAT is not known but it may involve contact with adipocytes and/or their associated vasculature. We hypothesize that the SNS innervation of WAT is an important contributor to the apparent “regulation” of total body fat.
289 citations
Patent•
17 May 2007
TL;DR: In this article, a method for the treatment of obesity or other disorders, by electrical activation or inhibition of the sympathetic nervous system, was described for the purpose of reducing food intake and increasing energy expenditure.
Abstract: A method is described for the treatment of obesity or other disorders, by electrical activation or inhibition of the sympathetic nervous system. This activation or inhibition can be accomplished by electrically stimulating the greater splanchnic nerve or other portion of the sympathetic nervous system using an implantable pulse generator. This nerve activation can result in reduced food intake and increased energy expenditure. Reduced food intake may occur through a variety of mechanisms that reduce appetite and cause satiety. Increased adrenal gland hormone levels will result in increased energy expenditure. Fat and carbohydrate metabolism, which are also increased by sympathetic nerve activation, will accompany the increased energy expenditure.
243 citations
Patent•
16 Aug 2005
TL;DR: In this paper, the authors describe devices and methods for the treatment of obesity or other disorders by electrical activation or inhibition of nerves using an electrode, which can be accomplished by stimulating a nerve using an electric motor controller.
Abstract: Devices (figure 5) and Methods for the treatment of obesity or other disorders by electrical activation or inhibition of nerves are described. This activation or inhibition can be accomplished by stimulating a nerve using an electrode. Dynamic stimulation through ramped cycling of electrical stimulation, stimulation frequency alteration, and/or duty cycle variance can produce therapeutic benefits.
236 citations
TL;DR: The sections in this article are: Arrangement of Vessels, Measurement of Flow, Vascular Exchange, and Responses to Humoral Agents.
Abstract: The sections in this article are:
1
Skin
1.1
Introduction
1.2
Arrangement of Vessels
1.3
Arteriovenous Anastomoses
1.4
Skin Vessels as Heat Exchangers
1.5
Measurement of Flow
1.6
Vasomotor Innervation
1.7
Reflex Control of Flow
1.8
Responses to Physical Stimuli
1.9
Responses to Humoral Agents
2
Adipose Tissue
2.1
Introduction
2.2
Arrangement of Vessels
2.3
Vascular Exchange
2.4
Measurement of Flow
2.5
Vasomotor Innervation
2.6
Reflex Control of Flow
2.7
Responses to Physical Stimuli
2.8
Responses to Humoral Agents
160 citations
References
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Journal Article•
TL;DR: The prostaglandins are a family of lipids, originally discovered over 30 years ago in human seminal fluid, which have since been found not only to have a wide variety of striking pharmacological actions, but also to be present in many if not all mammalian tissues.
Abstract: The prostaglandins are a family of lipids, originally discovered over 30 years ago in human seminal fluid, which have since been found not only to have a wide variety of striking pharmacological actions, but also to be present in many if not all mammalian tissues. They have an unusual chemical structure, being 20-carbon fatty acids derived enzymically from the essential fatty acids by cyclization and oxidation. Converting enzymes have been demonstrated in many tissues; they are especially active in the vesicular glands of the sheep, which are used for a practical method of biosynthesis.
The individual prostaglandins differ among themselves both qualitatively and quantitatively. Prostaglandins have a wide spectrum of biological action: They are smooth muscle stimulants, depressor peripheral vasodilators (except the PGFs which are pressor and venoconstrictor in dogs), and inhibitors of lipolysis, platelet aggregation and gastric secretion. In these areas, they are among the most potent compounds known, activity being present in some systems at concentrations of 0.01 ng/ml in vitro , and activity of 10 ng/kg in vivo . Prostaglandin formation and release is brought about by nerve activity, both central and peripheral. Their presence in biologically large concentrations in menstrual fluid and amniotic fluid at term is intriguing.
Physiological roles for these recently rediscovered compounds are yet to be established, but whenever substances are found in tissues which in very small doses can affect the function of these tissues, there is the possibility that they are regulators of physiological activity. Each effect of one or another prostaglandin suggests a corresponding physiological role, whether stimulatory or inhibitory, on such systems as smooth muscle, nerves, the circulation, and the reproductive organs. In the last named, roles in relation to fertilityand coitus and later possible action in relation to labor and postpartum uterine contraction have been proposed. Prostaglandins liberated by nerve stimulation, which then have actions opposite to that of the nerve stimulation, suggests a role as feed-back inhibitors. Thus, sympathetic nerve stimulation to adipose tissue induces both lipolysis and the release of antilipolytic prostaglandins, and vagal stimulation to the stomach, both secretion and the release of prostaglandins with powerful antisecretory actions. On the other hand, the ability of minute amounts of certain prostaglandins, inactive in their own right, to potentiate other agonists, suggests a more general role on ion transport or membrane function.
595 citations
Journal Article•
568 citations
TL;DR: The results show that pure bradykinin possesses all the actions of the crude mixture, that is, smooth-muscle stimulation, vasodilatation, increased capillary permeability and pain production.
Abstract: Bradykinin, first described by Rocha e Silva, Beraldo & Rosenfeld (1949), is one of a group of polypeptides called plasma kinins. Plasma kinins are known to stimulate certain types ofsmooth muscle, to cause vasodilatation, to increase capillary permeability and to produce pain when brought into contact with pain fibres. It has not been clear hitherto whether bradykinin is responsible for all these actions or whether several peptides are involved, as in all experiments crude extracts have been employed. However, recently bradykinin has been isolated (Elliott, Lewis & Horton, 1960a) and its structure determined (Elliott, Lewis & Horton, 1960b,c). It is therefore now possible to examine the actions of the pure peptide. The present investigation was carried out to answer the question, does the crude preparation of bradykinin contain one peptide having all the actions reported for the crude mixture, or does it contain a group of related peptides each of which is responsible for one or more of the biological actions? The results show that pure bradykinin possesses all the actions of the crude mixture, that is, smooth-muscle stimulation, vasodilatation, increased capillary permeability and pain production.
228 citations
TL;DR: The results suggest that the vasoconstrictor fibres, beside their powerful influence on the resistance and capacitance vessels, affect also the pre-capillary sphincters, which determine the number of capillaries open to flow.
Abstract: The influence of nervous and local chemical factors on the pre-capillary sphincter section of the muscle vascular bed has been studied in terms of changes in the filtration coefficient (CFC). The results suggest that the vasoconstrictor fibres, beside their powerful influence on the resistance and capacitance vessels, affect also the pre-capillary sphincters, which determine the number of capillaries open to flow. However, the influence exerted by the centrally controlled vasoconstrictor fibres on the pre-capillary sphincters in the skeletal muscles is rapidly overcome by ‘vasodilator metabolites’, accumulating when flow is reduced or metabolism is increased. Such local metabolic factors exert an especially powerful control of the sphincter section as compared with the neurogenic influence. Thus CFC in the skeletal muscles tends to rise at any decrease of blood flow/ tissue metabolism ratio e. g. from ‘resting’ values around 0.015 up to 0.04—0.05, during muscular exercise; an increase also occurs when flow is reduced. Flow reduction following mechanical arterial obstruction induces a relatively greater CFC increase than when flow is reduced by the constrictor fibres, which unmasks their weak but still significant influence on the pre-capillary sphincter section.
183 citations
TL;DR: The data indicate that sympathetic nerves to subcutaneous adipose tissue have the ability to mobilize energy for the organism within a few minutes.
Abstract: A 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.
163 citations