We have identified two distinct cellular responses that occur in human astrocytes in the presence of angiotensin (Ang) peptides and are linked to specific receptor subtypes. Ang II and the N-terminal heptapeptide Ang-(1-7) stimulated release of prostaglandin (PG) E2 and PGI2 (measured as the stable metabolite 6-keto-PGF1 alpha). In contrast, only Ang II but not Ang-(1-7) activated phosphoinosit...

Productive interaction between receptors and G proteins involves multiple intracellular receptor domains, but the role of individual receptor amino acids in directing the selection of specific signaling pathways has not yet been identified. Sequence alignment of several G protein-coupled receptors identified a highly conserved threonine residue in the i2 loop of the 5-hydroxytryptamine 1A (5-HT...

Fellner, Susan K., and William J. Arendshorst. Capacitative calcium entry in smooth muscle cells from preglomerular vessels. Am. J. Physiol. 277 (Renal Physiol. 46): F533– F542, 1999.—Calcium entry via voltage-gated L-type channels is responsible for at least half of the increase in cytosolic calcium ([Ca]i) in afferent arterioles following agonist stimulation. We sought the presence of capacit...

We describe several novel analogs of the seco-steroid 1,25(0H),-vitamin D,[1.25(OH),D3] and their effects on differentiation and proliferation of HL-60 human myeloid leukemic cells in vitro as well as their effects on calcium metabolism in vivo. The la-25(OH),-16ene-23yne-26,27Fo-vitamin D, is the most potent analog reported to date, having about 80-fold more activity than the reference 1,25(OH...

To assess cellular mechanisms mediating afferent (AA) and efferent arteriolar (EA) constriction by angiotensin II (AngII), experiments were performed using isolated perfused hydronephrotic kidneys. In the first series of studies, AngII (0.3 nM) constricted AAs and EAs by 29+/-3 (n = 8, P < 0.01) and 27+/-3% (n = 8, P < 0.01), respectively. Subsequent addition of nifedipine restored AA but not E...

Micromolar concentrations of ATP stimulate biphasic change in transepithelial conductance across CaSki cultures on filters, an acute transient increase (phase I response; triggered by P2Y(2) receptor and mediated by calcium mobilization-dependent cell volume decrease) followed by a slower decrease in permeability (phase II response). Phase II response is mediated by augmented calcium influx and...

Normal animals contain an autoreactive B lymphocyte subset, the B-1 subset, which is controlled by undefined mechanisms to prevent autoimmunity. Using a V(H)11V(kappa)9 Ig transgenic mouse, with a specificity prototypic of the subset, we have explored conditions responsible for the previously reported Ag hyporesponsiveness of these cells. We report that peritoneal V(H)11V(kappa)9 B cells exhibi...