Sodium—potassium adenosine triphosphatase

The ventricular action potential is depicted in Fig. 6-2.2 Myocyte resting membrane potential is usually -70 to -90 mV, due to the action of the sodium-potassium adenosine triphosphatase (ATPase) pump, which maintains relatively high extracellular sodium concentrations and relatively low extracellular potassium concentrations. During each action potential cycle, the potential of the membrane increases to a threshold potential, usually -60 to -80 mV. When the membrane potential reaches this threshold, the fast sodium channels open, allowing sodium ions to rapidly enter the cell. This rapid influx of positive ions... 

Of the following diuretic agents, which would be least likely to indirectly cause an increased binding of digoxin to cardiac tissue sodium-potassium-adenosine triphosphatase (Na K ATPase) ... 

One in vitro study on rat renal tissue homogenate showed barium weakly inhibited the sodium-potassium-adenosine triphosphatase enzyme system (Kramer et al. 1986). A second study on mouse kidney tubules showed barium chloride could depolarize the membrane and inhibit potassium transport (Volkl et al. 1987). A similar defect in cell membrane transport in humans could be responsible for the renal involvement observed in some cases of acute barium poisoning. 

Andrews PA, Mann SC, Huynh HH, Albright KD. Role of the sodium,potassium-adenosine triphosphatase in the accumulation of cis-diamminedichloroplatinum(II) in human ovarian carcinoma cells. Cancer Res. 1991 51 3677-3681. 

Thallium s mechanism of toxicity is related to its ability to interfere with potassium ion functions. Thallium interferes with energy production at essential steps in glycolysis, the Kreb s cycle, and oxidative phosphorylation. Other effects include inhibition of sodium-potassium-adenosine triphosphatase and binding to sulfhydryl groups. 

Schwartz, A., Lindenmayer, G. E., Allen, J. C. The sodium-potassium adenosine triphosphatase pharmacological, physiological and biochemical aspects. Pharmacol. Rev. 1975, 27, 3-134. 

Kl. Kaksis, C., Phillips, M. J., and Yousef, I. M., The respective roles of membrane cholesterol and of sodium potassium adenosine triphosphatase in the pathogenesis of lithocho-late-induced cholestasis. Lab. Invest. 43, 73-81 (1980). 

At relevant inotropic and vasorelaxant concentrations, milrinone is a selective inhibitor of peak III cAMP phosphodiesterase isozyme in cardiac and vascular muscle. This inhibitory action is consistent with cAMP-mediated increases in intracellular ionized calcium and contractile protein phosphorylation and relaxation in vascular muscle. Additional experimental evidence also indicates that milrinone is not a beta-adrenergic agonist nor does it inhibit sodium-potassium adenosine triphosphatase activity as do the digitalis glycosides. 

Among other pharmacodynamic drugs that are enzyme inhibitors are the cardiac glycosides which act on the heart by inhibiting sodium-potassium adenosine triphosphatase (Bonting, 1970) (see Section 14.1). 

Abdel-Latif, A.A., J. Brody, and H. Ramahi. Studies on sodium-potassium adenosine triphosphatase of the nerve endings and appearance of electrical activity in developing brain. J. Neurochem. 14 1133-1141, 1967. 

The most widely accepted mechanism of action of CGs involves the ability to inhibit the activity of the membrane-bound sodium-potassium-adenosine triphosphatase... 

Craig DS, Imtiaz AM, Kika A et al (2009) Inhibition of the sodium potassium adenosine triphosphatase pump sensitizes cancer cells to anoikis and prevents distant tumor formation. Cancer Res 69 2739-2747... 

Maintenance of critical ion concentrations via the sodium-potassium-adenOSine triphosphatase (ATPase) pump... 

The answer is 3 fCTiapter 8/7 B 2/. Cholestatic agents alter the ability of the bile canaliculi to transport bile salts. This activity may be related to osmotic changes caused by the secreted bile salts or to energy-dependent osmotic control accomplished through the sodium-potassium-adenosine triphosphatase (ATPase) pump. Cholestasis occurs in the bile canaliculi, and not in the common bile duct Kupffer cells, Disse s space, hepatic sinusoids, and the common bile duct are part of the hepatic parenchyma and are not directly involved in bile salt formation. 

Dahl, J. L., and Hokin, L. E., 1974, The sodium-potassium adenosine triphosphatase Anna. Rev, Biochem. 43 327. 

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