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Inhibition Of Diuretic Stimulation Of An Insect Secretory Epithelium By A Cgmp-Dependent Protein Kinase, Kristen A. Ruka, Anna P. Miller, Edward M. Blumenthal
Inhibition Of Diuretic Stimulation Of An Insect Secretory Epithelium By A Cgmp-Dependent Protein Kinase, Kristen A. Ruka, Anna P. Miller, Edward M. Blumenthal
Biological Sciences Faculty Research and Publications
The rate of urine secretion by insect Malpighian tubules (MTs) is regulated by multiple diuretic and antidiuretic hormones, often working either synergistically or antagonistically. In the Drosophila melanogaster MT, only diuretic factors have been reported. Two such agents are the biogenic amine tyramine (TA) and the peptide drosokinin (DK), both of which act on the stellate cells of the tubule to increase transepithelial chloride conductance. In the current study, TA and DK signaling was quantified by microelectrode recording of the transepithelial potential in isolated Drosophila MTs. Treatment of tubules with cGMP caused a significant reduction in the depolarizing responses to …
Isoform- And Cell-Specific Function Of Tyrosine Decarboxylase In The Drosophila Malpighian Tubule, Edward M. Blumenthal
Isoform- And Cell-Specific Function Of Tyrosine Decarboxylase In The Drosophila Malpighian Tubule, Edward M. Blumenthal
Biological Sciences Faculty Research and Publications
The biogenic amine tyramine (TA) is a potent diuretic factor when applied to the Malpighian tubule (MT) of Drosophila melanogaster, stimulating both urine production and transepithelial chloride conductance. Isolated MTs can respond not only to TA but also to its precursor, tyrosine; this observation led to the proposal that MTs are able to synthesize TA from applied tyrosine through the action of the enzyme tyrosine decarboxylase (TDC). In the current study it is shown that the non-neuronal isoform of TDC, Tdc1, is expressed in the principal cells of the MT. A mutant allele of Tdc1, Tdc1f03311 …
Modulation Of Tyramine Signaling By Osmolality In An Insect Secretory Epithelium, Edward M. Blumenthal
Modulation Of Tyramine Signaling By Osmolality In An Insect Secretory Epithelium, Edward M. Blumenthal
Biological Sciences Faculty Research and Publications
The control of water balance in multicellular organisms depends on absorptive and secretory processes across epithelia. This study concerns the effects of osmolality on the function of the Malpighian tubules (MTs), a major component of the insect excretory system. Previous work has shown that the biogenic amine tyramine increases transepithelial chloride conductance and urine secretion in Drosophila MTs. This study demonstrates that the response of MTs to tyramine, as measured by the depolarization of the transepithelial potential (TEP), is modulated by the osmolality of the surrounding medium. An increase in osmolality caused decreased tyramine sensitivity, whereas a decrease in osmolality …
Characterization Of Transepithelial Potential Oscillations In The Drosophila Malpighian Tubule, Edward M. Blumenthal
Characterization Of Transepithelial Potential Oscillations In The Drosophila Malpighian Tubule, Edward M. Blumenthal
Biological Sciences Faculty Research and Publications
The Malpighian tubule of Drosophila melanogaster is a useful model system for studying the regulation of epithelial ion transport. In acutely isolated tubules, the transepithelial potential (TEP) undergoes large oscillations in amplitude with a period of approximately 30s. The TEP oscillations are diminished by reductions in the peritubular chloride concentration in a manner consistent with their being caused by fluctuations in chloride conductance. The oscillations are eliminated by pretreating tubules with the calcium chelator BAPTA-AM, although removal of peritubular calcium has no effect, suggesting that the oscillations are a result of either the release of calcium from intracellular stores or …