Asset Details
Do you wish to reserve the book?
ACTIVE POTASSIUM TRANSPORT ACROSS THE ISOLATED TURTLE COLON
Hey, we have placed the reservation for you!
By the way, why not check out events that you can attend while you pick your title.
Oops! Something went wrong.
Looks like we were not able to place the reservation. Kindly try again later.
Are you sure you want to remove the book from the shelf?
ACTIVE POTASSIUM TRANSPORT ACROSS THE ISOLATED TURTLE COLON
Do you wish to request the book?
ACTIVE POTASSIUM TRANSPORT ACROSS THE ISOLATED TURTLE COLON
Please be aware that the book you have requested cannot be checked out. If you would like to checkout this book, you can reserve another copy
We have requested the book for you!
Your request is successful and it will be processed during the Library working hours. Please check the status of your request in My Requests.
Oops! Something went wrong.
Looks like we were not able to place your request. Kindly try again later.
Dissertation
ACTIVE POTASSIUM TRANSPORT ACROSS THE ISOLATED TURTLE COLON
1981
Overview
Although evidence has been obtained for active epithelial K transport, the cellular mechanisms responsible are not well understood. Progress in the study of epithelial K transport has been hindered by two problems: (1) the lack of a convenient model system in which K transport can be studied under conditions where the transepithelial driving forces can be readily controlled, (2) the inherent difficulties in discerning the contributions of the apical and basolateral membranes to transepithelial ion transport. The object of this study was to investigate the mechanisms of K transport in a simple epithelium, the colon of the freshwater turtle, which can be conveniently isolated from the animal, stripped of muscle and mounted as a flat sheet so that transepithelial electrochemical gradients can be readily controlled. The results clearly demonstrate that the turtle colon is capable of both active absorption and active secretion of K. A working hypothesis for active K transport was tested by examining the effect of ouabain and barium on K fluxes. In the turtle colon, K absorption was inhibited by mucosal ouabain and serosal barium. These observations support the concept of active apical K uptake, mediated by the Na:K ATPase, and conductive basolateral exit, via the barium-sensitive basolateral K channel. Potassium secretion was inhibited by serosal ouabain and mucosal barium which is consistant with K secretion driven by the basolateral Na:K pump, and passive apical exit via an apical K channel. A paracellular pathway exists in parallel with the cellular pathway for K flow. The selectivity of this pathway for K and Na is consistant with diffusion through a simple aqueous region. If a Na:K pump drives net Na absorption and K secretion, then an increase in pump rate should increase both ion flows. An increase in Na absorption, by increasing mucosal Na concentration, did not increase K secretion in the short-circuit state, but under open-circuit conditions K secretion was usually increased. These results demonstrate that the transcellular flows of K and Na, produced by active basolateral exchange of Na and K, can be dissociated such that independent regulation of Na absorption and K secretion is possible.
Publisher
ProQuest Dissertations & Theses
Subject
ISBN
9798660436055
