Recent evidence suggests that arginine vasopressin (AVP)-dependent aquaporin-2 expression is modulated by the extracellular calcium-sensing receptor (CaSR) in principal cells of the collecting duct, but the signaling pathways mediating this effect are unknown. Using a mouse cortical collecting duct cell line (mpkCCD(cl4)), we found that increasing the concentration of apical extracellular calci...

Hemichannels in the overlapping regions of apposing cells plasma membranes join to form gap junctions and provide an intercellular communication pathway. Hemichannels are also present in the nonjunctional regions of individual cells and their activity is gated by several agents, including calcium. However, their physiological roles are unknown. Using techniques of atomic force microscopy (AFM),...

Background: Tumor Necrosis Factor α (TNFα) upregulation during acute inflammatory response has been associated with numerous cardiac effects including modulating Connexin43 and vascular permeability. This may in turn alter cardiac gap junctional (GJ) coupling and extracellular volume (ephaptic coupling) respectively. We hypothesized that acute exposure to pathophysiological TNFα levels can modu...

Hemichannels in the overlapping regions of apposing cells plasma membranes join to form gap junctions and provide an intercellular communication pathway. Hemichannels are also present in the nonjunctional regions of individual cells and their activity is gated by several agents, including calcium. However, their physiological roles are unknown. Using techniques of atomic force microscopy (AFM),...

The effect of extracellular acidosis on contraction of single isolated ventricular cells from rabbit was measured in a system in which pHo could be changed in less than 200 msec. The contractile response to acidotic levels was complete within 25 seconds. The response was measured 30 seconds after pHo was decreased to 7.0, 6.5, 6.0, and 5.5 at each of 8 [Ca]o levels (0.125-4.0 mM). Cell shorteni...

The shear stress applied to lymphatic endothelial cells (LEC) by lymph flow changes dramatically under normal conditions as well as in response to disease conditions and immune reactions. In general, LEC are known to regulate the contraction frequency and strength of lymphatic pumping in response to shear stress. Intracellular calcium concentration ([Ca(2+)]i) is an important factor that regula...

Calcium to calcium exchange between intracellular and extracellular pools has been imaged directly in individual cells using stable 44Ca (98.78% enrichment) in the nutrient medium and an isotopic imaging technique, ion microscopy. Observations were made by imaging mass 40 to determine the native intracellular calcium (40Ca), and mass 44 to localize the 44Ca from the extracellular medium that ex...

To investigate the extent to which the properties of the cardiac myofibrils contribute to the length-force relation of cardiac muscle, we determined the sarcomere length-force relations for rat ventricular trabeculae both before and after the muscles were skinned with the detergent Triton X-100. Sarcomere length was measured continuously by laser diffraction. In the unskinned trabeculae stimula...

To study the modulatory effect of extracellular calcium on the whole cell K(+) currents (I(K)) in isolated Deiters cells, the whole cell K(+) currents were recorded when Deiters cells bathed in normal physiological solutions and calcium-free saline, respectively. The electrophysiological characteristics of I(K) currents were then analyzed with the patch clamp technique. Removing extracellular c...