Biomaterial Database

Mechanisms of transport of Na, Cl, and K in the human colon. 1978

P C Hawker, and K E Mashiter, and L A Turnberg

Ionic transport across isolated, stripped, human colonic mucosa was studied in vitro using a modified short circuit current technique. Electrical potential difference and short circuit current were dependent on the presence of sodium ions in the mucosal bathing solution and were unaffected by addition of 10 mM glucose to the solution. Ouabain (10(-3) M) added to the serosal reservoir abolished both potential difference and short circuit current. Isotopic flux measurements across short-circuited colonic mucosa showed a net active sodium absorption which accounted for the observed short circuit current and was unaffected by 10 mM glucose. Chloride was also actively absorbed and this was unaffected by removal of sodium from the bathing solutions. Ouabain abolished net sodium absorption but had no effect on chloride absorption. There was a net active secretion of potassium which was abolished in sodium-free buffer. We conclude that sodium is actively absorbed via a rheogenic process which is not stimulated by glucose; chloride is actively absorbed via a nonelectrogenic process, not linked to sodium transport, and probably involving a Cl-HCO3- exchange; and postassium is actively secreted possibly via a Na+K+ exchange.

UI	MeSH Term	Description	Entries
D007408	Intestinal Absorption	Uptake of substances through the lining of the INTESTINES.	Absorption, Intestinal
D007413	Intestinal Mucosa	Lining of the INTESTINES, consisting of an inner EPITHELIUM, a middle LAMINA PROPRIA, and an outer MUSCULARIS MUCOSAE. In the SMALL INTESTINE, the mucosa is characterized by a series of folds and abundance of absorptive cells (ENTEROCYTES) with MICROVILLI.	Intestinal Epithelium,Intestinal Glands,Epithelium, Intestinal,Gland, Intestinal,Glands, Intestinal,Intestinal Gland,Mucosa, Intestinal
D010042	Ouabain	A cardioactive glycoside consisting of rhamnose and ouabagenin, obtained from the seeds of Strophanthus gratus and other plants of the Apocynaceae; used like DIGITALIS. It is commonly used in cell biological studies as an inhibitor of the NA(+)-K(+)-EXCHANGING ATPASE.	Acocantherin,G-Strophanthin,Acolongifloroside K,G Strophanthin
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.
D002712	Chlorides	Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.	Chloride,Chloride Ion Level,Ion Level, Chloride,Level, Chloride Ion
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
D004560	Electricity	The physical effects involving the presence of electric charges at rest and in motion.
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D001692	Biological Transport	The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.	Transport, Biological,Biologic Transport,Transport, Biologic
D012964	Sodium	A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.	Sodium Ion Level,Sodium-23,Ion Level, Sodium,Level, Sodium Ion,Sodium 23