Zhong Tao Zhang

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BACKGROUND Obstructive jaundice damages critical functions in the liver. However, the mechanisms involved in hepatic dysfunction are obscure. Nitric oxide is implicated in liver injury under various pathological conditions. We previously reported that proinflammatory cytokine interleukin-1beta (IL-1beta) stimulated the production of nitric oxide in(More)
The alpha (catalytic) subunit of the Na+ pump (Na+, K(+)-ATPase) has three isoforms; alpha1 is ubiquitous, skeletal muscle expresses predominantly alpha2, and alpha3 has been localized to specific types of neurons and, possibly, to axonal processes. The alpha3 isoform mRNA is also expressed in the rat cardiac conduction system. Thus, we studied rat heart(More)
Perfusion of the renal medulla plays an important role in salt and water balance. Pericytes are smooth muscle-like cells that impart contractile function to descending vasa recta (DVR), the arteriolar segments that supply the medulla with blood flow. DVR contraction by ANG II is mediated by depolarization resulting from an increase in plasma membrane Cl(-)(More)
By participating in the regulation of ion and voltage gradients, the Na-K pump (i.e., Na,K-ATPase) influences many aspects of cellular physiology. Of the four alpha isoforms of the pump, alpha1 is ubiquitous, alpha2 is predominant in skeletal muscle, and alpha3 is found in neurons and the cardiac conduction system. To determine whether the isoforms have(More)
Rat descending vasa recta (DVR) express a tetrodotoxin (TTX)-sensitive voltage-operated Na(+) (Na(V)) conductance. We examined expression of Na(V) isoforms in DVR and tested for regulation of Na(V) currents by calmodulin (CaM). RT-PCR in isolated permeabilized DVR using degenerate primers targeted to TTX-sensitive isoforms amplified a product whose sequence(More)
We tested the hypothesis that constriction of descending vasa recta (DVR) is mediated by voltage-gated calcium entry. K(+) channel blockade with BaCl(2) (1 mM) or TEACl (30 mM) depolarized DVR smooth muscle/pericytes and constricted in vitro-perfused vessels. Pericyte depolarization by 100 mM extracellular KCl constricted DVR and increased pericyte(More)
We devised a method for removal of pericytes from isolated descending vasa recta (DVR). After enzymatic digestion, aspiration of a descending vas rectum into a micropipette strips the pericytes from the abluminal surface. Pericytes and denuded endothelia can be recovered for separate study. Using fura 2-loaded preparations, we demonstrated that 10 nM(More)
We tested whether K(+) channel inhibition accompanies ANG II-induced depolarization of descending vasa recta (DVR) pericytes. An increase in extracellular K(+) concentration ([K(+)](o)) from 5 to 100 mM depolarized resting pericytes but had no effect after prolonged (10 nM, 20 min) ANG II exposure. In contrast, reduction of extracellular Cl(-) concentration(More)
The PDZ domain adaptor protein Na+/H+ exchanger regulatory factor (NHERF)-2 is expressed in renal medullary descending vasa recta (DVR), although its function has not been defined. Transient receptor potential channels (TRPC) TRPC4 and TRPC5, nonselective cation channels that transport Ca2+, were recently demonstrated to complex with the NHERF proteins. We(More)
We tested whether chronic ANG II infusion into rats affects descending vasa recta (DVR) contractility, synthesis of superoxide, or synthesis of nitric oxide (NO). Rats were infused with ANG II at 250 ng.kg(-1).min(-1) for 11-13 days. DVR were loaded with dihydroethidium (DHE) to measure superoxide and 3-amino-4-aminomethyl-2',7'-difluorofluorescein (DAFFM)(More)