Modulation of tyramine signaling by osmolality in an insect secretory epithelium

• DOI: 10.1152/ajpcell.00026.2005
• Publication Date: 2005-06-30T00:25:13Z
• Authors: Edward M. Blumenthal
• Keywords: Tyramine

The control of water balance in multicellular organisms depends on absorptive and secretory processes across epithelia. This study concerns the effects osmolality function Malpighian tubules (MTs), a major component insect excretory system. Previous work has shown that biogenic amine tyramine increases transepithelial chloride conductance urine secretion Drosophila MTs. demonstrates response MTs to tyramine, as measured by depolarization potential (TEP), is modulated surrounding medium. An increase caused decreased sensitivity, whereas decrease resulted increased sensitivity; changes +/-20% nearly 10-fold modulation 10 nM tyramine. activity another diuretic agent, leucokinin, was similarly sensitive osmolality, suggesting occurs downstream receptor. In continuous signaling, likely vivo, TEP oscillates, an lengthened period these oscillations. Increased also rate production; this attenuated tyraminergic antagonist yohimbine. A model proposed which signaling enhances conservation body during dehydration stress. ligand novel effect may be widespread mechanism through epithelia respond their environment.