Cholesterol Metabolism and Vitamin B6. III. The Stimulation of Hepatic Cholesterogenesis in the Vitamin B6-Deficient Rat

1971 ◽  
Vol 49 (8) ◽  
pp. 933-935 ◽  
Author(s):  
C. M. Hinse ◽  
P. J. Lupien
Keyword(s):  
Vitamin B6 ◽  
Cholesterol Metabolism ◽  
Krebs Cycle ◽  
Pool Size ◽  
Liver Slices ◽  
Liver Homogenates ◽  
The Difference ◽  
Hepatic Cholesterogenesis ◽  
Stimulation Of

The rate of incorporation of labeled acetate into cholesterol by liver slices of pyridoxine-deficient rats was found to be three times that of control rats; with liver homogenates the difference between the two groups was even greater. Using the CO2 trapping technique, a 30% decrease in the hepatic acetate pool size was observed in pyridoxine-deficient rats and a 20% increase in pair-fed rats. Activity of the Krebs cycle was decreased by a third in the pair-fed rats.

Enhanced coupling of adenylate cyclase to lipolysis in permeabilized adipocytes from trained rats

1991 ◽  
Vol 71 (1) ◽  
pp. 23-29 ◽  
Author(s):  
T. Izawa ◽  
T. Komabayashi ◽  
T. Mochizuki ◽  
K. Suda ◽  
M. Tsuboi
Keyword(s):  
Adenylate Cyclase ◽  
Dose Response ◽  
Response Curve ◽  
Positive Relationship ◽  
Regression Coefficient ◽  
Permeabilized Cells ◽  
Major Mechanism ◽  
The Difference ◽  
And Control ◽  
Stimulation Of

Digitonin-permeabilized adipocytes were used to study the coupling of adenylate cyclase (AC) to lipolysis in exercise-trained rats. Isoproterenol-(IPR) stimulated lipolysis in permeabilized cells was significantly greater in trained than in control rats. Under essentially identical conditions, the dose-response curve for IPR stimulation of AC activity in the absence of 3-isobutyl-1-methylxanthine was similar in trained and control rats. However, the potency of stimulation by IPR as a percentage of the basal level was greater in trained rats. AC activity and lipolysis in the presence of 3-isobutyl-1-methylxanthine were also significantly greater in trained than in control rats. Least-squares analysis by plotting the log AC vs. lipolysis values showed that the regression coefficient was about three-fold greater in trained than in control rats. The concentration of endogenous adenosine 3′,5′-cyclic monophosphate (cAMP) needed to produce a half-maximal lipolytic response was 18.58 and 10.81 pmol.min-1.10(6) cells-1 in control and trained rats, respectively. Thus a positive relationship existed between lipolysis and AC activity, with a tighter coupling in trained rats. Lipolysis in response to exogenous cAMP tended to be greater in trained than in control rats, and the difference was statistically significant for 50 microM and 10 mM cAMP. Our finding support the concept that the major mechanism of enhanced lipolysis in trained rats was an increase in the activity of enzymatic step(s) distal to cAMP.

Responses of Medullary Dorsal Horn Neurons to Corneal Stimulation by CO2 Pulses in the Rat

1999 ◽  
Vol 82 (5) ◽  
pp. 2092-2107 ◽  
Author(s):  
Harumitsu Hirata ◽  
James W. Hu ◽  
David A. Bereiter
Keyword(s):  
Thalamic Nucleus ◽  
Receptive Fields ◽  
Male Rats ◽  
Cervical Cord ◽  
Type I ◽  
Type Ii ◽  
Upper Cervical ◽  
The Difference ◽  
Evoked Activity ◽  
Stimulation Of

Corneal-responsive neurons were recorded extracellularly in two regions of the spinal trigeminal nucleus, subnucleus interpolaris/caudalis (Vi/Vc) and subnucleus caudalis/upper cervical cord (Vc/C1) transition regions, from methohexital-anesthetized male rats. Thirty-nine Vi/Vc and 26 Vc/C1 neurons that responded to mechanical and electrical stimulation of the cornea were examined for convergent cutaneous receptive fields, responses to natural stimulation of the corneal surface by CO2 pulses (0, 30, 60, 80, and 95%), effects of morphine, and projections to the contralateral thalamus. Forty-six percent of mechanically sensitive Vi/Vc neurons and 58% of Vc/C1 neurons were excited by CO2 stimulation. The evoked activity of most cells occurred at 60% CO2 after a delay of 7–22 s. At the Vi/Vc transition three response patterns were seen. Type I cells ( n = 11) displayed an increase in activity with increasing CO2 concentration. Type II cells ( n = 7) displayed a biphasic response, an initial inhibition followed by excitation in which the magnitude of the excitatory phase was dependent on CO2 concentration. A third category of Vi/Vc cells (type III, n = 3) responded to CO2 pulses only after morphine administration (>1.0 mg/kg). At the Vc/C1 transition, all CO2-responsive cells ( n = 15) displayed an increase in firing rates with greater CO2 concentration, similar to the pattern of type I Vi/Vc cells. Comparisons of the effects of CO2 pulses on Vi/Vc type I units, Vi/Vc type II units, and Vc/C1 corneal units revealed no significant differences in threshold intensity, stimulus encoding, or latency to sustained firing. Morphine (0.5–3.5 mg/kg iv) enhanced the CO2-evoked activity of 50% of Vi/Vc neurons tested, whereas all Vc/C1 cells were inhibited in a dose-dependent, naloxone-reversible manner. Stimulation of the contralateral posterior thalamic nucleus antidromically activated 37% of Vc/C1 corneal units; however, no effective sites were found within the ventral posteromedial thalamic nucleus or nucleus submedius. None of the Vi/Vc corneal units tested were antidromically activated from sites within these thalamic regions. Corneal-responsive neurons in the Vi/Vc and Vc/C1 regions likely serve different functions in ocular nociception, a conclusion reflected more by the difference in sensitivity to analgesic drugs and efferent projection targets than by the CO2 stimulus intensity encoding functions. Collectively, the properties of Vc/C1 corneal neurons were consistent with a role in the sensory-discriminative aspects of ocular pain due to chemical irritation. The unique and heterogeneous properties of Vi/Vc corneal neurons suggested involvement in more specialized ocular functions such as reflex control of tear formation or eye blinks or recruitment of antinociceptive control pathways.

scholarly journals On the Non-Specific Stimulation of Agglutinins. With Especial Reference to the Enteric Fevers and Typhus Fever

1929 ◽  
Vol 28 (4) ◽  
pp. 418-448 ◽  
Author(s):  
A. Felix
Keyword(s):  
Qualitative Method ◽  
Published Data ◽  
Enteric Infection ◽  
Widal Test ◽  
Enteric Infections ◽  
The Difference ◽  
Specific Stimulation ◽  
Enteric Group ◽  
Typhus Fever ◽  
Stimulation Of

(1) The review of the published data furnishes additional evidence in support of the view that no technique whatsoever, Dreyer's technique included, based on the quantitative method of the agglutination reaction hitherto used, is capable of affording a differentiation between inoculation and infection agglutinins.(2) These techniques are concerned always exclusively in the demonstration of the labilotropic H agglutinins ofB. typhosusandB. paratyphosusA. and B. and it is the behaviour of these agglutinins that is the responsible factor in producing the phenomena.(3) In various febrile conditions in inoculated individuals these H agglutinins undergo a re-stimulation resulting in a curve of agglutination which is indistinguishable from that due to specific stimulation. The re-stimulation of the labilotropic inoculation agglutinins is of the same nonspecific character (i.e.heterologous) in the course of enteric infections as in the course of other febrile diseases.(4) The observation of this non-specific re-stimulation is independent of the technique used; living bacilli and suspensions preserved with phenol or formalin (Dreyer's technique included) do not in this respect behave differently.(5) The proposed qualitative method for the Widal test depends, in inoculated individuals, exclusively upon the behaviour of the stabilotropic O agglutinins. In their presence it is capable of affording the certain diagnosis of an enteric infection; in their absence the negative result of the test is not conclusive; if T.A.B. vaccine has been used it is only possible to diagnose enteric group without being able to differentiate typhoid from paratyphoid A. or B.; if T. vaccine has been used then A. or B. infection can be differentiated but not T.(1) The conclusions previously arrived at by means of the qualitative method of the Widal test were fully confirmed. By eliminating the labilotropic H agglutinins from any consideration—in the case of previously sensibilised individuals—agglutination due to the specific stimulation in active enteric infection can be distinguished definitely from that due to the nonspecific re-stimulation by various febrile diseases.(2) Normal and immune O agglutinins forB. typhosusandB. paratyphosusA. and B., as well as those forB. proteusX 19, are not liable to non-specific stimulation in the course of various febrile diseases.(3) One more of the supposed differences in nature between the Widal test and the Weil-Felix test is thereby eliminated.(4) The difference in the response to non-specific stimulation shown to exist in stabilotropic and labilotropic agglutination seems more likely to be one of degree than one in nature and needs further investigation.

Extra Force From Asynchronous Stimulation of Cat Soleus Muscle Results From Minimizing the Stretch of the Common Elastic Elements

2006 ◽  
Vol 96 (3) ◽  
pp. 1401-1405 ◽  
Author(s):  
Thomas G. Sandercock
Keyword(s):  
Low Frequency ◽  
Muscle Length ◽  
Test Frequency ◽  
The Common ◽  
Tension Curve ◽  
Ventral Roots ◽  
The Difference ◽  
Dynamic Stretch ◽  
Elastic Elements ◽  
Stimulation Of

Rack and Westbury showed that low-frequency asynchronous stimulation of a muscle produces greater force compared with synchronous stimulation. This study tested the hypothesis that the difference results from the dynamic stretch of the common elastic elements. In eight anesthetized cats, the soleus was attached to a servomechanism to control muscle length and record force. The ventral roots were divided into four bundles so each innervated approximately 1/4 of the soleus. The elasticity shared by each part of the muscle was estimated and the servomechanism programmed to compensate for its stretch. At each test frequency (5, 7.5, and 10 Hz), the muscle was stimulated by asynchronous stimulation, synchronous stimulation, summation of force with each part stimulated individually, and summation with each part stimulated individually and the servomechanism mimicking tendon stretch during asynchronous stimulation. Muscle length was isometric except for the last protocol. The observed differences were small. The greatest difference occurred during stimulation at 5 Hz with muscle length on the ascending limb of the length-tension curve. Here, the average forces, normalized by asynchronous force, were asynchronous, 100%; synchronous, 73%; summation, 110%; and summation with stretch compensation, 98%. The results support the hypothesis and suggest that the common elasticity can be used to predict force gains from asynchronous stimulation.

scholarly journals Dietary Vitamin B6 Deficiency Impairs Gut Microbiota and Host and Microbial Metabolites in Rats

Biomedicines ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 469
Author(s):  
Shyamchand Mayengbam ◽  
Faye Chleilat ◽  
Raylene A. Reimer
Keyword(s):  
Gut Microbiota ◽  
Vitamin B6 ◽  
Dietary Vitamin ◽  
Enzymatic Reactions ◽  
Sprague Dawley ◽  
Microbial Composition ◽  
Metabolic Markers ◽  
Vitamin B6 Deficiency ◽  
The Difference ◽  
The Impact

Vitamin B6 plays a crucial role as a cofactor in various enzymatic reactions but bacteria-produced vitamin B6 is not sufficient to meet host requirements. Our objective was to assess the impact of diet-derived vitamin B6 on gut microbiota and host serum metabolomics. Sprague–Dawley rats (n = 47) were fed a control, low B6 (LB6) or high B6 (HB6) diet for six weeks. Serum and cecal samples were collected for biochemical, metabolomics and gut microbiota profiling. There was a significant sex effect for gut microbiota and several metabolic markers. Bodyweight and percent body fat were significantly reduced in LB6 compared to control and HB6 rats. Microbial beta-diversity differed significantly between LB6 and the control and HB6 rats in both sexes. Lachnospiraceae_NK4A136_group and Bacteroides were the primary taxa driving the difference between LB6 and control. There was a significant separation of cecal and serum metabolites of LB6 compared to control and HB6 rats. In the cecum, arginine biosynthesis was impaired, while vitamin B6 metabolism, lysine degradation and nicotinate and nicotinamide metabolism were impaired in serum metabolite profiles. Cecal propionate and butyrate were significantly reduced in LB6 rats irrespective of sex. Host vitamin B6 deficiency but not excess significantly alters gut microbial composition and its metabolites.

Insulin stimulus of leucine incorporation into frog liver protein

1962 ◽  
Vol 203 (4) ◽  
pp. 687-689 ◽  
Author(s):  
J. C. Penhos ◽  
M. E. Krahl
Keyword(s):  
Amino Acid ◽  
Rat Liver ◽  
Leucine Incorporation ◽  
Liver Protein ◽  
Amino Acid Incorporation ◽  
Insulin Effect ◽  
Acid Incorporation ◽  
Liver Slices ◽  
Stimulation Of

Slices prepared from livers of bull frogs ( Rana catesbiana), pancreatectomized and/or hypophysectomized 7 days before, were incubated 2 hr in frog Ringer-bicarbonate solution at 25 C. Incorporation of leucine-1-C14 into protein was subnormal in the pancreatectomized series. The addition of insulin in vitro, with glucose also present in the medium, produced a significant ( P < 0.01) stimulation of amino acid incorporation in the following series: livers from normal fed animals; livers from animals pancreatectomized 7 days before; and livers from animals pancreatectomized and hypophysectomized 7 days before. Neither insulin nor glucose alone gave a significant effect. These results therefore confirm and extend those obtained with rat liver slices showing that insulin can stimulate amino acid incorporation into protein when added directly to liver. The effect is relatively greatest with livers from animals pancreatectomized 7 days before; the insulin effect does not depend on the presence of the pituitary, as it is obtainable with livers from animals hypophysectomized and pancreatectomized 7 days previously.

Endothelium inhibits norepinephrine release from adrenergic nerves of rabbit carotid artery

1988 ◽  
Vol 254 (5) ◽  
pp. H871-H878 ◽  
Author(s):  
R. A. Cohen ◽  
R. M. Weisbrod
Keyword(s):  
Carotid Artery ◽  
Adrenergic Nerves ◽  
Adrenergic Nerve ◽  
Norepinephrine Release ◽  
Physical Barrier ◽  
Rabbit Carotid Artery ◽  
Vessel Lumen ◽  
Donor Artery ◽  
The Difference ◽  
Stimulation Of

The overflow of endogenous norepinephrine caused by transmural electrical stimulation or depolarization with potassium was smaller in superfused segments of the rabbit carotid artery with intact endothelium than in segments denuded of endothelium. In segments preincubated with [3H]norepinephrine, the lesser overflow was found to be partially due to metabolism by the endothelium of the neurotransmitter. Even after treatment to block the disposition of norepinephrine, the endothelium acted as a partial physical barrier to the overflow of norepinephrine into the lumen of arteries superfused and perfused selectively. However, a lesser overflow of norepinephrine to the adventitia of the artery accounted for the majority of the difference in overflow between segments with and without endothelium. The inhibition by the endothelium of the overflow of norepinephrine from adrenergic nerves was unaffected by blocking prejunctional alpha 2-adrenoceptors, prostaglandin synthesis, free radicals, or guanylate cyclase. Vasodilators released from the endothelium of a donor artery inhibited contractions caused by adrenergic nerve stimulation of a bioassay artery but failed to inhibit norepinephrine release. These observations indicate that the endothelium 1) metabolizes norepinephrine, 2) acts as a physical barrier to its overflow into the blood vessel lumen, and 3) inhibits the release of the adrenergic transmitter from adrenergic nerves.

Differential Patterns of Spinal Sympathetic Outflow Involving a 10-Hz Rhythm

1999 ◽  
Vol 82 (2) ◽  
pp. 841-854 ◽  
Author(s):  
Gerard L. Gebber ◽  
Sheng Zhong ◽  
Craig Lewis ◽  
Susan M. Barman
Keyword(s):  
Brain Stem ◽  
Phase Angle ◽  
Sympathetic Nerves ◽  
Phase Relations ◽  
Sympathetic Outflow ◽  
Free Running ◽  
The Difference ◽  
Electrical Stimuli ◽  
The Brain ◽  
Stimulation Of

Time and frequency domain analyses were used to examine the changes in the relationships between the discharges of the inferior cardiac (CN) and vertebral (VN) postganglionic sympathetic nerves produced by electrical activation of the midbrain periaqueductal gray (PAG) in urethan-anesthetized, baroreceptor-denervated cats. CN-VN coherence and phase angle in the 10-Hz band served as measures of the coupling of the central oscillators controlling these nerves. The 10-Hz rhythm in CN and VN discharges was entrained 1:1 to electrical stimuli applied to the PAG at frequencies between 7 and 12 Hz. CN 10-Hz discharges were increased, and VN 10-Hz discharges were decreased when the frequency of PAG stimulation was equal to or above that of the free-running rhythm. In contrast, stimulation of the same PAG sites at lower frequencies increased, albeit disproportionately, the 10-Hz discharges of both nerves. In either case, PAG stimulation significantly increased the phase angle between the two signals (VN 10-Hz activity lagged CN activity); coherence values relating their discharges were little affected. However, the increase in phase angle was significantly more pronounced when the 10-Hz discharges of the two nerves were reciprocally affected. Importantly, partialization of the phase spectrum using the PAG stimuli did not reverse the change in CN-VN phase angle. This observation suggests that the increase in the CN-VN phase angle reflected changes in the phase relations between coupled oscillators in the brain stem rather than the difference in conduction times to the two nerves from the site of PAG stimulation. In contrast to the effects elicited by PAG stimulation, stimulation of the medullary lateral tegmental field induced uniform increases in the 10-Hz discharges of the two nerves and no change in the CN-VN phase angle. Our results demonstrate that changes in the phase relations among coupled brain stem 10-Hz oscillators are accompanied by differential patterns of spinal sympathetic outflow. The reciprocal changes in CN and VN discharges produced by PAG stimulation are consistent with the pattern of spinal sympathetic outflow expected during the defense reaction.

EFFECT OF ERUCIC ACID ON INCORPORATION OF ACETATE-1-C14 INTO CHOLESTEROL AND FATTY ACIDS

1959 ◽  
Vol 37 (7) ◽  
pp. 803-810 ◽  
Author(s):  
K. K. Carroll
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Erucic Acid ◽  
Cholesterol Metabolism ◽  
Young Male ◽  
Male Rats ◽  
Acetate Incorporation ◽  
Acid Incorporation ◽  
Liver Slices ◽  
Fatty Acid Incorporation

Young male rats were fed synthetic diets containing either no fat or various individual fatty acids for 3 to 4 weeks. They were then killed and the incorporation of acetate-1-C14 into cholesterol and fatty acids was measured in liver slices and in scrapings of intestinal mucosa. Acetate incorporation into cholesterol by liver slices was much greater in animals fed erucic acid than in those fed no fat, palmitic, stearic, oleic, or linoleic acids. A marked differential was not observed in fatty acid incorporation but values tended to be higher on the fat-free and erucic acid diets. Erucic acid did not stimulate acetate incorporation into cholesterol by mucosa and in general mucosa seemed to be less sensitive to changes in diet. The results are discussed in relation to previously observed effects of erucic acid on cholesterol metabolism.

EFFECTS OF ALIPHATIC ALCOHOLS ON THE METABOLISM OF GLUCOSE AND FRUCTOSE IN RAT LIVER SLICES

1963 ◽  
Vol 41 (3) ◽  
pp. 793-803 ◽  
Author(s):  
Edward Majchrowicz ◽  
J. H. Quastel
Keyword(s):  
Rat Liver ◽  
Liver Slice ◽  
Inhibitory Effect ◽  
Aliphatic Alcohols ◽  
Isotopic Dilution ◽  
Acetyl Coa ◽  
Radioactive Carbon ◽  
Liver Slices ◽  
The Difference ◽  
Ethanol Ethanol

Ethanol, at concentrations up to 3 mM, whilst having little inhibitory effect on the production of respiratory CO2of rat liver slices, has a marked suppressing action on the formation of labelled CO2from labelled glucose. The suppression of C14O2formation by ethanol from radioactive glucose is independent of the concentration of the latter and amounts to 57% with 3 mM ethanol after 1 hour's incubation. The results are consistent with the conclusion that ethanol gives rise more rapidly than glucose to acetyl CoA and that the large suppressing action of ethanol in rat liver slices is due to isotopic dilution of labelled acetyl CoA derived from the labelled sugars with the unlabelled acetyl CoA derived from ethanol. Ethanol exercises a larger inhibition of the rate of C14O2formation from glucose-6-C14than from glucose-1-C14. The difference between the effects of ethanol on C14O2formation from glucose-1-C14and glucose-6-C14is presumably due to operation of the hexosemonophosphate shunt.The higher aliphatic alcohols have about the same diminishing effect on C14O2formation from glucose-U-C14and fructose-U-C14as does ethanol. This observation may also be a consequence of dilution of labelled acetyl CoA derived from the sugars by unlabelled acetyl CoA coming from the added alcohol. Incorporation of radioactive carbon from the labelled sugars into liver proteins and lipids is inhibited by ethanol and higher aliphatic alcohols, and the inhibitions are similar in magnitude to those of C14O2formation. These may be accounted for by isotopic dilution. The amounts of C14incorporated into lipids and proteins from radioactive glucose and fructose are small, being about 1/10th of that appearing in the CO2.The higher aliphatic alcohols suppress total CO2formation during rat liver slice respiration much more than does ethanol at equivalent concentrations.

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