טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentRozman Alexander
SubjectControl and Localization of Chloride Conductance in
Amphibian Skin Epithelium
DepartmentDepartment of Biology
Supervisor Professor Uri Katz


Abstract

In amphibians, the skin epithelium plays a central role in gas exchange and osmoregulation, in addition to defense and insulation. The aim of the present research was the study the properties of the chloride conductance pathway which is localized to the mitochondria-rich cells (MRC) in the amphibian skin epithelium, with special emphasis on the control mechanisms. Representative species that exhibit different features of this pathway were selected for this study, and were compared.


The following conclusions can be deduced from this study:

·        The transporting pathway is controlled by adrenergic systems. Different responses where recognized between species: in the toad Bufo viridis skin the chloride conductance is inhibited by α1-adrenergic system and is not affected by β-adrenergic system, in spite of its presence in MRC; in the frog Rana pipiens skin the conductance is less sensitive to inhibition by α1-adrenergic system and exhibit intensification upon activation of β-adrenergic system.

·        IBMX affects the transporting pathway in two ways: 1) via direct binding to regulatory subunit of the pathway as is the case in skins of both B. viridis and R. pipiens; 2) via PDE inhibition that results in increase of cellular cAMP as was found in the R. pipiens skin.

·        Acidification of apical solution resulted in complete and reversible inhibition of the voltage-activated chloride conductance.

·        The results substantiate and support other studies that are localizing the chloride conductance to MRC. However, the molecular basis of the transporting pathway remains to be verified.