scholarly journals Modulation ofβ-Cell Ouabain-SensitiveR86b+Influx (Na+/k+Pump) by D-Glucose, Glibenclamide or Diazoxide

2000 ◽  
Vol 1 (4) ◽  
pp. 265-274 ◽  
Author(s):  
Adrian Elmi ◽  
Lars-ÅKe Idahl ◽  
Janove Sehlin
Keyword(s):  
Atpase Activity ◽  
Direct Effect ◽  
Mechanism Of Action ◽  
The Other ◽  
Pump Function ◽  
Other Hand ◽  
Insulin Secretagogues ◽  
Pre Treatment ◽  
Effect Of Glucose ◽  
Stimulation Of

The activity of theβ-cellNa+/k+pump was studied by using ouabain-sensitive (lmM ouabain)R86b+influx inβ-cell-rich islets of Umeå-ob/obmice as an indicator of the pump function. The present results show that the stimulatory effect of glucose on ouabain-sensitiveR86b+influx reached its approximate maximum at 5mM glucose. Pre-treatment of the islets with 20mM glucose for 60 min strongly reduced the glucose-induced stimulation of theNa+/k+pump. Pre-treatment (60 or 180 min) of islets at 0mM glucose, on the other hand, did not affect the magnitude of the glucose-induced stimulation ofR86b+influx dunng the subsequent 5-min incubation. Glibenclamide stimulated the ouabain-sensitiveR86b+uptake in the same manner as glucose. The stimulatory effect, showed its apparent maximum at 0.5μM. Pre-treatment (60 min) of islets with 1μM glibenclamide did not reduce the subsequent stimulation of the ouabain-sensitiveR86b+influx. The stimulatory effect of glibenclamide and D-glucose were not .additive, suggesting that they may have the same mechanism of action. No direct effect of glibenclamide (0.01-1μM) was observed on theNa+/k+ATPase activity in homogenates of islets. Diazoxide (0.4mM) inhibited theNa+/k+pump. This effect was sustained even after 60 min of pre-treatment of islets with 0.4mM diazoxide. The stimulatory effect of glibenclamide and D-glucose were abolished by diazoxide. It is concluded that nutrient as well as non-nutrient insulin secretagogues activate theNa+/k+pump, probably as part of the membrane repolarisation process.

EFFECT OF ACTINOMYCIN D ON TSH-INDUCED STIMULATION OF THYROIDAL PROTEIN SYNTHESIS IN THE RAT

1974 ◽  
Vol 77 (1) ◽  
pp. 64-70 ◽  
Author(s):  
Gustav Wägar
Keyword(s):  
Protein Synthesis ◽  
Actinomycin D ◽  
The Other ◽  
Leucine Incorporation ◽  
Short Term ◽  
Other Hand ◽  
Thyroid Glands ◽  
Translational Level ◽  
Stimulation Of

ABSTRACT Whether the short-term regulation of thyroidal protein synthesis by TSH occurs at the transcriptional or the translational level was tested by measuring the effect of actinomycin D (act D) on the TSH-induced stimulation of L-14C-leucine incorporation into the thyroidal proteins of rats. TSH was injected 6 h before the rats were killed. The thyroid glands were then removed and incubated in vitro in the presence of L-14C-leucine for 2 h. The pronounced stimulation of leucine incorporation in the TSH-treated animals was depressed as compared with controls but still significant even when the animals had been pre-treated with 100 μg act D 24 and 7 h before sacrifice. On the other hand, act D strongly decreased incorporation of 3H-uridine into RNA. Short-term regulation of thyroidal protein synthesis by TSH appears to be partly but not wholly dependent on neosynthesis of RNA. Hence regulation may partly occur at the translation level of protein synthesis.

On Research and Other Matters

1922 ◽  
Vol 26 (140) ◽  
pp. 325-330
Author(s):  
S. Heckstall Smith
Keyword(s):  
British Empire ◽  
Air Force ◽  
The Other ◽  
Other Hand ◽  
Secretary Of State ◽  
The Press ◽  
The Subject ◽  
Stimulation Of

If the thought of another war troubles you, then don't read this article. If you would rather say to yourself as the Secretary of State said to the Air Conference, “ There won't be another war for ten years, so why worry? ” then no doubt you will think with him that it is better to let other nations have alk the bother and expense of trying to advance; after all, we are jolly fine fellows and can soon pick up. If, on the other hand, you have imagination which gives you a nasty queasy sensation when you think of what might be, then perhaps the following notes, albeit disjointed and mostly stale, may at least conjure up in you thoughts of your own on the subject. This is all that is needed to help, our advancement in the air–the stimulation of spoken and written thoughts by the British nation, for if every taxpayer in the British Empire says “ Air Force,” then the Press and Parliament will say it too.

Localization of Spontaneous Respiratory Neuronal Activities in the Medulla Oblongata of the Cat: A New Location of the Expiratory Center

1957 ◽  
Vol 190 (2) ◽  
pp. 350-355 ◽  
Author(s):  
Edgar Haber ◽  
Kurt W. Kohn ◽  
S. H. Ngai ◽  
D. A. Holaday ◽  
S. C. Wang
Keyword(s):  
Vagus Nerve ◽  
Reticular Formation ◽  
Medulla Oblongata ◽  
Electric Stimulation ◽  
The Other ◽  
Drug Induced ◽  
Other Hand ◽  
Twin Beam ◽  
New Location ◽  
Stimulation Of

Medulla oblongata of 80 vagotomized cats was explored with microelectrodes. Spontaneous respiratory neuronal activities and chest movements were recorded simultaneously with a twin beam cathode ray oscilloscope. It was found that inspiratory discharges are concentrated in the reticular formation between 3 mm rostral and 1 mm caudal to the level of the obex, which corresponds approximately to the inspiratory region of Pitts, Magoun and Ranson. On the other hand, expiratory discharges are not obtained in Pitts' expiratory area, but are found in a circumscribed region in the reticular formation from the level of the obex to 3 mm caudally. Electric stimulation of this region has been found recently by Ngai and Wang to yield marked expiratory spasm. It is concluded that the expiratory center is located caudally to the inspiratory center in the cat. The spontaneous respiratory neuronal discharges continue with no alterations of pattern of firing during drug-induced respiratory paralysis, and are increased both in number and in frequency during CO2 inhalation. Stimulation of the vagus nerve with 50 shocks/sec. reduces inspiratory discharges and prolongs the duration of expiratory discharges.

Trypanosoma cruzi Epimastigotes Express the Ouabain-and Vanadate-Sensitive (Na++K+)ATPase Activity

1998 ◽  
Vol 53 (11-12) ◽  
pp. 1049-1054 ◽  
Author(s):  
Celso Caruso-Neves ◽  
Marcelo Einicker-Lamas ◽  
Carlos Chagas ◽  
Mecia Maria Oliveira ◽  
Adalberto Vieyra ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Atpase Activity ◽  
The Other ◽  
Other Hand ◽  
P Type

Abstract The presence of (Na++K+)ATPase activity in CL14 clone and NIH NTY strain of Trypano­soma cruzi epimastigotes is demonstrated. A Na+ plus K+ stimulated ATPase activity is found in both strains. The optimal Na+/K+ ratio is 5:1 and 9:1 in CL14 clone and NIH NTY strain, respectively. In both strains, vanadate completely inhibits the ouabain-sensitive ATPase activ­ity indicating that it belongs to the P-type (E 1/E2) family of ion-transporting ATPases. The I50 for vanadate is 0.66 ± 0.04 and 0.04 ± 0.02 μᴍ in CL14 clone and NIH NTY strain, respectively. These data indicate that both strains of T. cruzi epimastigotes express the oua­ bain-and vanadate-sensitive (Na++K+)ATPase activity. On the other hand, the discrepancy between the parameters analyzed for the inhibitors suggests that they express different iso­ forms of this enzyme.

Saccadic eye movements evoked by microstimulation of the fastigial nucleus of macaque monkeys

1988 ◽  
Vol 60 (3) ◽  
pp. 1036-1052 ◽  
Author(s):  
H. Noda ◽  
S. Murakami ◽  
J. Yamada ◽  
J. Tamada ◽  
Y. Tamaki ◽  
...  
Keyword(s):  
Eye Movements ◽  
White Matter ◽  
Purkinje Cells ◽  
Saccadic Eye Movements ◽  
The Other ◽  
Fastigial Nucleus ◽  
Threshold Region ◽  
Other Hand ◽  
Low Threshold ◽  
Stimulation Of

1. Systematic exploration throughout the deep cerebellar nuclei and white matter disclosed that the region from which saccadic eye movements (saccades) were evoked with weak currents (less than 10 microA) was confined to the fastigial nucleus and the adjacent white matter. 2. When an electrode for stimulation was advanced in the cerebellum, saccades were evoked in the direction of the stimulated side (ipsilateral saccades) as it entered the low-threshold region. In some tracks, particularly when the electrode was advanced in the medial portion of the fastigial nucleus, the direction of the evoked saccades changed from the ipsilateral to the contralateral. 3. The mappings with microstimulation disclosed that the ipsilateral saccades were elicited from a relatively wide region that included almost the full extent of the fastigial nucleus. The low-threshold region continued in the white matter caudally into vermal lobule VII and rostrally into the dorsal aspect of the brachium conjunctivum. On the other hand, the contralateral saccades were evoked from a relatively circumscribed region in the ventromedial portion of the fastigial nucleus. 4. The reversal in the direction of the horizontal component occurred always in a narrow zone in the core of the fastigial nucleus. The caudal part of this zone coincided with an ellipsoidal region where anterogradely labeled axons of the Purkinje cells terminated when HRP was injected into vermal lobule VII. 5. When bicuculline (0.2-1 microgram) was injected in the ellipsoidal region, the ipsilateral saccades evoked from the dorsocaudal aspect of the region were suppressed for several hours. On the other hand, the contralateral saccades evoked from the ventromedial portion of the fastigial nucleus were either unchanged or enhanced. 6. Because the ipsilateral saccades were suppressed by bicuculline, they were most probably evoked by stimulation of the presynaptic component of gamma-amino-butyric acid-(GABA) mediated synapses, namely the axons of Purkinje cells. 7. Because stimulation of the presynaptic component of the inhibitory synapses evoked ipsilateral saccades, activation of the postsynaptic component would evoke contralateral saccades. In fact, the distribution of the fastigial sites yielding contralateral saccades coincided with the course of axons of fastigial neurons arising in the ellipsoidal region. It is most likely, therefore, that the contralateral saccades were evoked by stimulation of fastigial neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

Corticotropin- and lysine-vasopressin induced changes of plasma corticosteroids and testosterone in the adult male pig

1980 ◽  
Vol 95 (4) ◽  
pp. 518-522 ◽  
Author(s):  
W. Hahmeier ◽  
M. Fenske ◽  
L. Pitzel ◽  
W. Holtz ◽  
A. König
Keyword(s):  
Body Weight ◽  
Intravenous Injection ◽  
Intravenous Administration ◽  
The Other ◽  
Plasma Testosterone ◽  
Elevated Plasma ◽  
Other Hand ◽  
Lysine Vasopressin ◽  
Pre Treatment ◽  
Induced Changes

Abstract. Intravenous injection of 10.0 μg/kg body weight synthetic corticotropin (1-24 ACTH) into chronically cannulated boars resulted in significantly elevated plasma corticosteroid and testosterone levels between 20 and 140 min (corticosteroids) and 20–80 min (testosterone) after injection. Administration of lysine-vasopressin (LVP) at doses of 0.1, 0.2 and 0.4 IU/kg body weight elicited a significant increase of plasma corticosteroids between 20 and 40 min after injection; on the other hand, plasma testosterone concentrations tended to fall when compared to pre-treatment levels. From our results it can be concluded that exogenously applied ACTH can effectively stimulate the release of corticosteroids and testosterone. Intravenous administration of LVP results in significantly, although not maximally increased plasma corticosteroid concentrations; the release of endogenous ACTH induced by LVP injection, on the other hand, appeared to be too small to stimulate testosterone release significantly.

scholarly journals THE NERVOUS MECHANISM OF COORDINATION IN THE CRINOID, ANTEDON ROSACEUS

1924 ◽  
Vol 6 (3) ◽  
pp. 281-288 ◽  
Author(s):  
A. R. Moore
Keyword(s):  
Ventral Side ◽  
Ventral Surface ◽  
Reciprocal Inhibition ◽  
The Other ◽  
Dynamic Symmetry ◽  
Other Hand ◽  
Stimulation Of

1. Stimulation causes Antedon to swim by means of alternate oral bending and dorsal stroke of the arms. Two arms of a given ray move alternately so that while one is executing the aboral stroke its mate is flexing ventrally. This implies reciprocal inhibition. 2. Recriprocal inhibition between the two arms of an isolated ray can be abolished by the use of either strychnine or nicotine. 3. Coordination between the rays is referable to the conducting properties of the nervous pentagon which connects the five rays. In this system an impulse loses in effectiveness as it passes from the point of origin. 4. When Antedon is made to rest oral face down on the floor of an aquarium, oral flexion of all the rays, swimming movements, and righting result. Antedon is therefore negatively stereotropic with reference to its ventral side. 5. Excitation of the dorsal cirri results in aboral bending of all the rays. Stimulation of the cirri inhibits ventral flexion to the extent of preventing righting movements while on the other hand stimulation of the ventral surface inhibits the grasp reflex of the cirri. Thus oral and aboral sides of Antedon exhibit dynamic symmetry although structurally dissimilar.

Hormonal regulation of hepatic glycine oxidation

1993 ◽  
Vol 44 (3) ◽  
pp. 473 ◽  
Author(s):  
M Jois ◽  
JT Brosnan
Keyword(s):  
Direct Effect ◽  
Hormonal Regulation ◽  
Inorganic Phosphate ◽  
Protein S ◽  
Calcium Mobilization ◽  
The Other ◽  
Isolated Mitochondria ◽  
Cytosolic Protein ◽  
Hepatic Oxidation ◽  
Stimulation Of

Hormones which regulate hepatic oxidation of glycine include glucagon, catecholamines and vasopressin. The stimulation of oxidation of glycine by glucagon requires cyclic nucleotidedependent phosphorylation of one or more cytosolic proteins and does not involve mobilization of calcium from intracellular stores. The stimulation of glycine oxidation by catecholamines and vasopressin, on the other hand, appears to involve calcium mobilization. While calcium has direct effect on mitochondrial glycine oxidation, the link between phosphorylation of cytosolic protein(s) and mitochondrial glycine oxidation is not known. The stimulation of glycine oxidation by hormones can be demonstrated in mitochondria isolated from rats treated with hormones prior to sacrifice. Both the effects of glucagon and calcium are evident in isolated mitochondria only when inorganic phosphate is included in the medium. These findings are discussed in relation to the regulation of hepatic glycine oxidation.

Assessment of the Effect of C-Peptide Level on Na-K ATPase Activity In Individuals with Type II Diabetic Peripheral Neuropathy

2021 ◽  
Vol 53 (03) ◽  
pp. 213-219
Author(s):  
Eman H Al-Rikabi ◽  
Keyword(s):  
Enzyme Activity ◽  
Diabetic Neuropathy ◽  
Atpase Activity ◽  
Negative Correlation ◽  
Clinical Symptoms ◽  
The Other ◽  
C Peptide ◽  
Other Hand ◽  
Peptide Level

Background: Both Type 1 and Type 2 diabetes can cause neuropathy, which is a frequent and severe consequence. C-peptide depletion may be partly related to in the occurrence of certain diabetic complications. It has been demonstrated that even a little amount of residual C-peptide has a considerable metabolic advantage. Objective: The study’s objective was to predict the relation of plasma C-peptide levels in patients with diabetic neuropathy, and its effect on Na-K ATPase activity. Design and Methods: In this case-control study, 150 individuals have been included: 80 patients with diabetic neuropathy, 40 diabetics without neuropathy and 30 non-diabetic subjects as a control. Patients in the first group were carefully chosen based on their clinical symptoms and nerve conduction studies results. The assessment of plasma C-peptide was done by ELISA, Na-K ATPase enzyme activity by spectrophotometer, and HbA1C by HPLC. Results: Mean plasma C-peptide level and Erythrocyte Na-K ATPase activity were substantially lower in neuropathy type 2 DM patients compared to diabetes without neuropathy and control (p= 0.002, 0.000 respectively). The negative correlation between C-peptide with HbA1c, and diabetes period were all negligible (p= 0.447,0.098), Even though there was a notable negative correlation with age (p= 0.03). On the other hand, the relationship linking C-peptide and Na-K ATPase enzyme activity was shown to be insignificant (p=0.69). Conclusions: Diabetic neuropathy is related to a low C-peptide level. The association between C-peptide and Na-K ATPase enzyme activity, on the other hand, was shown to be insignificant. C-peptide HbA1c, and duration of diabetes all had minor negative associations.

CORTICOID PRODUCTION IN VITRO AS A TEST OF ADRENOCORTICAL FUNCTION IN RATS

1960 ◽  
Vol XXXIII (I) ◽  
pp. 59-66 ◽  
Author(s):  
J. van der Vies
Keyword(s):  
Adrenal Cortex ◽  
Adrenal Function ◽  
The Other ◽  
Adrenocortical Function ◽  
Experimental Conditions ◽  
Adrenal System ◽  
Other Hand ◽  
Stimulation Of

ABSTRACT Adrenal function in rats under various experimental conditions was studied by incubating the adrenals in vitro and determining the corticosteroid output during one hour. This in vitro corticoid production was reduced after hypophysectomy, hypothalamus-lesioning and treatment with hydrocortisone or with Nembutal and morphine. On the other hand, an increased production was observed following stimulation of the pituitary-adrenal system by exogenous histamine or corticotrophin. From these experiments it is concluded that the corticoid production in vitro reflects the activity of the adrenal cortex in vivo and hence can be used for the study of the latter function.

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