In neuronal cells, opioid peptides and opiates inhibit neurotransmitter release, which is a calcium-dependent process. They also inhibit adenylyl cyclase, presumably via the membrane signal-transducing component, Gi, a guanine nucleotide-binding protein (G-protein). No causal relationship between these two events has yet been demonstrated. Besides Gi,… (More)
The inhibition of voltage-dependent Ca2+ channels in secretory cells by plasma membrane receptors is mediated by pertussis toxin-sensitive G proteins. Multiple forms of G proteins have been described, differing principally in their alpha subunits, but it has not been possible to establish which G-protein subtype mediates inhibition by a specific receptor.… (More)
Voltage-dependent Ca2+ currents appear to be involved in the actions of hormones that regulate pituitary secretion. In order to investigate modulation of Ca2+ currents by release-inducing and release-inhibiting hormones, we performed whole-cell clamp experiments in the pituitary cell line GH3. The resting potential was approximately -40 mV; spontaneous… (More)
shadow zone in the lee side of Terceira island is identified. It is influenced jointly by wave refraction and diffraction. Furthermore, a cross-sea pattern revealed in the image spectra is investigated. The cross sea is generated by the diffracted wave rays from the northern and southern coasts of the island. Less wave directional spreading for the… (More)
G proteins act as transducers between membrane receptors activated by extracellular signals and enzymatic effectors controlling the concentration of cytosolic signal molecules such as cAMP, cGMP, inositol phosphates and Ca2+. In some instances, the receptor/G protein-induced changes in the concentration of cytosolic signal molecules correlate with activity… (More)
— A new method for wind-field retrieval with spatially and temporally high-resolution using marine radar-image sequences is presented. The method is based on analyzing the movement of wind gusts, which become visible in radar image sequences after filtering. In contrast to previous methods, this new technique requires no calibration phase of the radar… (More)
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In plasma membranes of human neutrophils, we identified two major pertussis toxin substrates of 40 kDa Mr with pI values of 5.30 and 5.37. Only the acidic of the two substrates was also present in neutrophil cytosol. Two-dimensional tryptic peptide maps revealed a high degree of homology of cytosolic and particulate substrates. Purified G-protein beta… (More)