Microglia (support cells in the brain) are connected by gap junctions. When the
ID: 53241 • Letter: M
Question
Microglia (support cells in the brain) are connected by gap junctions. When the fluorescent dye Lucifer yellow is injected into individual microglia that are part of a large group of cells, dye passes to other cells. When microglia are treated with the calcium ionophore, 4Br-A23187, there is a dramatic decrease in dye passage between cells. Which of the following is correct?
a ) "The passage of molecules between cells can be regulated by the intracellular Ca2+ content. When the Ca2+ concentration is increased in an individual cell, the movement of fluorescent molecules into that cell is increased, suggesting that gap junctions are open under these conditions.
b) The passage of molecules between cells can be regulated by the intracellular Ca2+ content. When the Ca2+ concentration is increased outside an individual cell, the movement of fluorescent molecules into that cell is inhibited, suggesting that gap junctions are closed under these conditions.
c) The passage of molecules between cells can be regulated by the intracellular Ca2+ content. When the Ca2+ concentration is increased in an individual cell, the movement of fluorescent molecules from that cell is inhibited, suggesting that gap junctions are closed under these conditions.
d) The passage of molecules between cells can be regulated by the intracellular Ca2+ content. When the Ca2+ concentration is increased outside an individual cell, the movement of fluorescent molecules from that cell is inhibited, suggesting that gap junctions are closed under these conditions.
Explanation / Answer
a ) "The passage of molecules between cells can be regulated by the intracellular Ca2+ content. When the Ca2+ concentration is increased in an individual cell, the movement of fluorescent molecules into that cell is increased, suggesting that gap junctions are open under these conditions.