Biomaterial Database

Amiloride sensitivity of the transepithelial electrical potential and of sodium and potassium transport in rat distal colon in vivo. 1981

C J Edmonds

1. The effect of amiloride within the gut lumen on the transepithelial electrical potential difference (p.d.) and Na and K transport by the distal colon of adrenalectomized (dexamethasone-maintained), normal, aldosterone-infused and Na-depleted groups of rats was examined. 2. Amiloride had no effect in adrenalectomized rats; in normal rats, only the p.d. was significantly reduced. 3. In the group given a short (2 hr) aldosterone infusion, amiloride reduced the elevated p.d. and K secretion rate to normal levels. There was no change in apparent K permeability of the epithelium. 4. In the Na-depleted group, p.d. and Na absorption were virtually abolished by amiloride but although K secretion was reduced it still remained much above normal levels. Adrenalectomy prevented the effects of Na depletion. 5. P.d. change occurred rapidly when amiloride was added to the perfusate. Increasing the Na concentration in the perfusate reduced the sensitivity to amiloride. Apparent 'Km' values estimated from p.d. changes (luminal Na, 50 mM) were similar for aldosterone-infused (7.6 X 10(-6) M) and Na-depleted (5.4 X 10(-6) M) rats. 6. Aldosterone appears to be essential for the induction of amiloride-sensitive Na paths in the mucosal plasma membrane of rat colonic epithelial cells. Prolonged aldosterone stimulation, as in the Na-depleted rats, increases the amiloride-sensitive Na paths while largely suppressing the amiloride-insensitive Na paths; in addition, the K/Na clearance rate ratio of the epithelium is increased. AMiloride interacts only with one set of Na paths and does not interact directly with K paths.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D011188	Potassium	An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
D011719	Pyrazines	A heterocyclic aromatic organic compound with the chemical formula C4H4N2.	Pyrazine
D003106	Colon	The segment of LARGE INTESTINE between the CECUM and the RECTUM. It includes the ASCENDING COLON; the TRANSVERSE COLON; the DESCENDING COLON; and the SIGMOID COLON.	Appendix Epiploica,Taenia Coli,Omental Appendices,Omental Appendix,Appendices, Omental,Appendix, Omental
D004848	Epithelium	The layers of EPITHELIAL CELLS which cover the inner and outer surfaces of the cutaneous, mucus, and serous tissues and glands of the body.	Mesothelium,Epithelial Tissue,Mesothelial Tissue,Epithelial Tissues,Mesothelial Tissues,Tissue, Epithelial,Tissue, Mesothelial,Tissues, Epithelial,Tissues, Mesothelial
D000315	Adrenalectomy	Excision of one or both adrenal glands. (From Dorland, 28th ed)	Adrenalectomies
D000450	Aldosterone	A hormone secreted by the ADRENAL CORTEX that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium.	Aldosterone, (+-)-Isomer,Aldosterone, (11 beta,17 alpha)-Isomer
D000584	Amiloride	A pyrazine compound inhibiting SODIUM reabsorption through SODIUM CHANNELS in renal EPITHELIAL CELLS. This inhibition creates a negative potential in the luminal membranes of principal cells, located in the distal convoluted tubule and collecting duct. Negative potential reduces secretion of potassium and hydrogen ions. Amiloride is used in conjunction with DIURETICS to spare POTASSIUM loss. (From Gilman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 9th ed, p705)	Amidal,Amiduret Trom,Amiloberag,Amiloride Hydrochloride,Amiloride Hydrochloride, Anhydrous,Kaluril,Midamor,Midoride,Modamide,Anhydrous Amiloride Hydrochloride,Hydrochloride, Amiloride,Hydrochloride, Anhydrous Amiloride,Trom, Amiduret
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia