Department Chair

I. Martha Skerrett

Date of Award

8-2017

Access Control

Open Access

Degree Name

Biology, M.A.

Department

Biology Department

Advisor

Derek L. Beahm

Department Home page

biology.buffalostate.edu

First Reader

Derek L. Beahm

Second Reader

I. Martha Skerrett

Third Reader

Gregory J. Wadsworth

Abstract

Cell volume changes are associated with both normal and disease processes, and can serve as a signal for altering cell activities. Most cell types in a multicellular organism express gap junction channels that allow for the direct transfer of ions, metabolites, and other small molecules between neighboring cells. Little is known about the potential role of gap junctions in modulating cell volume dynamics. The present study characterizes what happens to the swelling rates of fast swelling and slow swelling cells when they are coupled together by gap junctions. The initial hypothesis was that water transport through gap junctions from a fast swelling cell would increase the swelling rate of the slow swelling cell. I first verified endogenous gap junction communication in CHO cell lines stably transfected to express either the water channel AQP4 to create a fast swelling cell type or CD81 membrane protein to create a normal slow swelling cell type. Relative volume changes associated with exposure to a 30% hypo-osmotic shock were measured in CHO-AQP4 and CHO-CD81 homogeneous populations and in mixed populations. Swelling curves were fit to a single exponential function for homogeneous populations or a double exponential for mixed populations. Average time constants (tau) of these fits were compared between the different groups, with CHO-AQP tau=9.7s whereas CHO-CD81 tau=40.6s. The fast and slow tau of mixed populations were 7.4 sec and 34.2 sec, respectively. There was a trend for both cell types to reach their new volumes faster when cocultured. Attempts to block gap junctions with a non-specific inhibitor, carbenoxolone, generated mixed results. Models to explain the data, as well as the advantages and disadvantages of the experimental strategy, are discussed to help direct future studies on the role of gap junctions in cell volume dynamics.

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