EurekaMag.com logo
+ Site Statistics
References:
48,253,228
Abstracts:
22,798,842
+ Resolve Accession
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
Submit PDF Full TextSubmit PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on Google+Follow on Google+
Follow on LinkedInFollow on LinkedIn

+ Translate

The electrogenic sodium potassium pump of mouse pancreatic beta cells


, : The electrogenic sodium potassium pump of mouse pancreatic beta cells. Journal of Physiology (Cambridge) 332: 529-552

The contribution of the Na pump to the membrane potential of mouse pancreatic .beta.-cells was studied with micro-electrodes. In 0 or 3 mM glucose, ouabain rapidly (within 2 min) depolarized the .beta.-cell membrane by an average of 7 mV, whereas K omission hyperpolarized it markedly. In 6 or 7 mM glucose, ouabain still produced depolarization, but K omission had no consistent effect. Both induced electrical activity in certain cells. In 10 mM glucose, withdrawal of ouabain or K re-introduction caused a transient hyperpolarization with suppression of electrical activity. Duration and amplitude of the hyperpolarization increased with the time of pump blockade and with the concentration of ouabain. The hyperpolarization following K readmission was abolished by ouabain and that following ouabain withdrawal was prevented by K omission. Readmission of various K concentrations showed that the hyperpolarization was not due to depletion of K just outside of the membrane. In 10 mM glucose, the membrane potential of .beta.-cells exhibited repetitive slow waves with bursts of spikes on the plateau. These electrical events were modified by ouabain in a dose-dependent manner. The frequency of the slow waves augmented markedly because of an increase in the slope of the pre-potential and a shortening of the intervals; the slope of their repolarization phase decreased, but their duration was not changed. Omission of K increased the slope of the pre-potential and the frequency of the slow waves. It also accelerated their repolarization phase and reduced their duration, likely because of the increase in driving force for K efflux. Increasing K concentration to 8 mM slowed the repolarization phase and lengthened the slow waves without changing their frequency. Even when K permeability of the .beta.-cell membrane was increased by high extracellular Ca, ouabain and K omission augmented the frequency of the slow waves. In 0 or 10 mM glucose, ouabain increased 86Rb+ efflux from perifused islets, whereas K omission decreased it. In 10 mM glucose, a marked decrease in 86Rb+ efflux accompanied ouabain withdrawal and K re-introduction. The hyperpolarization is thus not due to an increase in K permeability. In pancreatic .beta.-cells, the Na pump is truly electrogenic, contributes to the resting potential and modulates the slow waves of membrane potential induced by glucose. Rapid changes in insulin release occurring upon inhibition or activation of the Na pump may thus be due to the changes in .beta.-cell membrane potential.

(PDF 0-2 workdays service)

Order PDF Full Text

Close
Close

Click here to order any other PDF Full Text


Accession: 006670394

PDF Full Text: Submit


Submit PDF Full Text

No spam - Every submission is manually reviewed

Due to poor quality, we do not accept files from Researchgate

Submitted PDF Full Texts will always be free for everyone
(We only charge for PDFs that we need to acquire)

Select a PDF file:
Close
Close

Other references

Roemer T.; Lober R.; Matuszewski F.; Nikschick S., 1991: Prophylactic consequences from retrospective studies in tubal sterility and ectopic pregnancy. 181 women, who have been operated on tubal sterility, and 172 women, who have been operated on an ectopic pregnancy as well as 241 women with nontubal sterility and 181 fertile women have been the basis for a retrospective search for anamnestic ri...

Allison, B. J.; Morrison, A., 1951: Two ready reckoners for use in volume calculations. The first table gives under every quarter-girth (QG) from 2 in. to 25 3/4) in. the equivalent sectional area, calculated as Sectional area = (QG)2/144 sq ft. The second table given for each QG at breast height, the corresponding sectional area at...

Tucek S.; Ricny J.; Dolezal V., 1982: Acetyl coenzyme a and control of the synthesis of acetyl choline in the brain. Experimental work concerning the relation between the availability of acetylCoA and the synthesis of acetylcholine in the [rat] brain was reviewed and discussed from the viewpoint of the mass action (reaction equilibrium) hypothesis of the control...

Rola Pleszcznyski M.; Blanchard R., 1981: Abnormal suppressor cell function in atopic dermatitis. The status of suppressor cells in patients with atopic dermatitis was studied. As a group, they showed absent concanavalin A-inducible suppressor cell function as measured by proliferative responses to pokeweed mitogen and decreased function as me...

Arroyo C.M., 1990: Esr spectroscopic studies of endothelial dependent relaxation factor in endothelial neuroblastoma and macrophages cells. Free Radical Biology & Medicine 9(SUPPL 1): 37

Walker D.; Davie A., 1990: A comparison of the relative sensitivity of two types of heaf gun. A total of 696 secondary school children were given a Heaf test in one forearm with a magnetic head Heaf gun and in the other forearm with a fixed head gun. One week later the results were read blind. In 333 (48%) children the fixed head gun gave...

Kennedy, WJ.; Wright, CW., 1984: The Cretaceous ammonite Ammonites requienianus d'Orbigny, 1841. Coilopoceras requienianum (d'Orbigny, 1841) is revised on the basis of the types and other material. It shows wide intraspecific variation and dimorphism of the type demonstrated in North American species of the genus. Similar dimorphism is s...

Little J.B., 1971: Effects of a substance released by mammalian cells in stationary cultures which promotes the repair of potentially lethal radiation damage. Radiation Research 47(1): 340-341

Vlasak, M; Bares, I1; Sehnalova, Jo, 1981: Results of studying genetic resources of Triticum durum wheat directed at productivity increase Scientific-Research Institute of Crop Production in Praha-Ruzyne, Czechoslovakia.1. Sbornik Simpoziuma SEVa na temu "Izuchenie i ispol'zovanie istochnikov genov poleznykh rastenii tropikov i subtropikov": 13-15 sentiabria 1981 vedecky redaktor: Pavel Valicek

Tielsch J.M.; Katz J.; Singh K.; Quigley H.A.; Gottsch J.D.; Javitt J.; Sommer A., 1991: A population based evaluation of glaucoma screening the baltimore eye survey. The Baltimore Eye Survey was a population-based survey conducted from January 1985 to November 1988 among residents of east Baltimore, Maryland, who were 40 years of age or older. A total of 5,308 black subjects and white subjects received a compr...