2002 Global Researcher Conference Proceeding
April 26 - 28, 2002
|Conference:||2002 Global Researcher Conference|
|Title:||Regulation of Aquaporin-2 trafficking by Vasopressin in Renal Collecting Duct: Roles of Ryanodine-Sensitive Ca2+ Stores and Calmodulin|
|Institution:||National Institutes of Health|
Cells within a portion of the kidney called the collecting duct help the kidney regulate water by allowing water to be reabsorbed from urine into the blood when the body is dehydrated. This reabsorption process is initiated when the hormone, vasopressin, triggers a molecular sequence that moves the protein, aquaporin-2, from within the IMCD cells to the cells' outer membrane.
Knepper, et al., investigated the role of calcium, specifically Ca2+, in this water reabsorption process. They found that vasopressin induces an increase in Ca2+ within the cells of microdissected kidney collecting ducts. This increase was blocked when the researchers added BAPTA, a molecular compound which restricts the movement of Ca2+ by binding to it, to microdissected collecting ducts. BAPTA also blocked the vasopressin-induced increase in water flow through the cells.
The Ryadodine receptor is a molecular structure which plays a role in Ca2+ regulation in cells. When Knepper, et al., prevented it releasing calcium into the cell interior, vasopressin lost its ability to increase water movement through the cells. Similar results were seen when the researchers inhibited the action of calmodulin, a protein in cells which responds to increases in intracellular calcium by altering cell function.