We tested the hypothesis that left atrial (LA) myocytes are more sensitive to acetylcholine (ACh) than right atrial (RA) myocytes, which results in a greater dose-dependent increase in LA than RA ...rotor frequency, increased LA-to-RA frequency gradient and increased incidence of wavelet formation during atrial fibrillation (AF).
AF was induced in seven Langendorff-perfused sheep hearts in the presence of ACh (0.1-4.0 microM) and studied using optical mapping and bipolar recordings. Dominant frequencies (DFs) were determined in optical and electrical signals and phase movies were used to identify rotors and quantify their dynamics. DFs in both atria increased monotonically with ACh concentration until saturation, but the LA frequency predominated at all concentrations. Rotors were also seen more often in the LA, and although their life span decreased, their frequency and number of rotations increased. Patch-clamp studies demonstrated that ACh-activated potassium current (I(K,ACh)) density was greater in LA than RA sheep myocytes. Additionally, ribonuclease protection assay demonstrated that Kir3.4 and Kir3.1 mRNAs were more abundant in LA than in RA.
A greater abundance of Kir3.x channels and higher I(K,ACh) density in LA than RA myocytes result in greater ACh-induced speeding-up of rotors in the LA than in the RA, which explains the ACh dose-dependent changes in overall AF frequency and wavelet formation.
Effects of the imidazoline compound RX871024 on cytosolic free Ca2+ concentration (Ca2+i) and insulin secretion in pancreatic β-cells from SUR1 deficient mice have been studied. In β-cells from ...wild-type mice RX871024 increased Ca2+i by blocking ATP-dependent K+-current (KATP) and inducing membrane depolarization. In β-cells lacking a component of the KATP-channel, SUR1 subunit, RX871024 failed to increase Ca2+i. However, insulin secretion in these cells was strongly stimulated by the imidazoline. Thus, a major component of the insulinotropic activity of RX871024 is stimulation of insulin exocytosis independently from changes in KATP-current and Ca2+i. This means that effects of RX871024 on insulin exocytosis are partly mediated by interaction with proteins distinct from those composing the KATP-channel.
Soviet Theater Censorship Zaitsev, Mark
The Drama Review: TDR,
06/1975, Letnik:
19, Številka:
2
Journal Article
Recenzirano
Stanislavsky once observed that “One theatrical production can tell you incomparably more about a foreign country than a whole series of lectures, libraries, books, or years of theoretical study.” ...This is particularly true in the Soviet Union today, where the theatre, in addition to its official role as a major tool of education and indoctrination, serves as an increasingly important outlet for the expression of ideas and the airing of dissatisfactions still largely excluded from the printed page.
And given the present social and political climate, it surely is no coincidence that one of the major unofficial themes in the Soviet theatre today is that of censorship and freedom of expression. As the chant goes in Yuri Lyubimov's production
Under the Skin of the Statue of Liberty
(see T57), “If only three minutes of truth! If only three minutes of truth!” Although sung by a chorus of American students, the message's real target is hardly lost on those sitting in the audience at the Taganka Theatre in Moscow.
Introductory experiments with a projected 30 GHz/5 MW/30 dB three-cavity gyroklystron 1 are described. The electron gun was tested in a configuration with self-excited cavity: the 50% efficiency at ...the 12 MW output power of the oscillator confirmed the high quality of the electron beam. At the first experiment with the gyroklystron, 3.5 MW output power at 18 % efficiency and 27 dB gain were obtained at 0.5 μs pulse duration.
PDF
