Modulating Ca influx into adrenal chromaffin cells with short-duration nanosecond electric pulses.

Isolated bovine adrenal chromaffin cells exposed to single 2-, 4-, or 5-ns pulses undergo a rapid, transient rise in intracellular Ca mediated by Ca entry via voltage-gated Ca channels (VGCCs), mimicking the activation of these cells in vivo by acetylcholine. However, pulse durations 150 ns or longer elicit larger amplitude and longer-lived Ca responses due to Ca influx via both VGCCs and a yet to be identified plasma membrane pathway(s). To further our understanding of the differential effects of ultrashort versus longer pulse durations on Ca influx, chromaffin cells were loaded with calcium green-1 and exposed to single 3-, 5-, 11-, 25-, or 50-ns pulses applied at their respective Ca activation threshold electric fields.

A protein tyrosine phosphatase inhibitor, pervanadate, inhibits angiotensin II-Induced beta-arrestin cleavage.

Beta-arrestins turn off G protein-mediated signals and initiate distinct G protein-independent signaling pathways. We previously demonstrated that angiotensin AT(1) receptor-bound beta-arrestin 1 is cleaved after Phe(388) upon angiotensin II stimulation. The mechanism and signaling pathway of angiotensin II-induced beta-arrestin cleavage remain largely unknown.

Kinetics of CCR7 expression differ between primary activation and effector memory states of T(H)1 and T(H)2 cells.

We explored the kinetics of CCR7 expression on T(H)1 and T(H)2 polarized cells as well as on antigen-specific T cell lines at various stages of differentiation. A striking pattern of early (days 7-14) inducible CCR7 expression was seen preferentially on primary T(H)1 cell lines, as compared to T(H)2 cells, and was dependent on the strength and duration of the T cell receptor signal. Upon repeated restimulation (days 21-28) and differentiation, a switch occurred in which T(H)2 cells had high CCR7 expression, whereas T(H)1 cells lost CCR7 expression.

Chemokine receptor expression on MBP-reactive T cells: CXCR6 is a marker of IFNgamma-producing effector cells.

Cytokine-polarized T cells have distinct chemokine receptor (CKR) expression patterns associated with their cytokine secretion profiles. In order to investigate this paradigm in autoreactive human T cells, we have determined the CKR expression pattern of myelin basic protein (MBP)-reactive T cell lines (TCL) and compared these profiles to those of TCL-generated in response to tetanus toxoid (TT). Expression of CXCR6 and CXCR3 on TCL was significantly positively correlated with IFNgamma, and inversely correlated with IL-5 production.