RESUMEN
Paramecium exhibits responsive behavior to environmental changes, moving either closer to or further away from stimuli. Electrophysiological experiments have revealed that these behavioral responses are controlled by membrane potentials. Anoctamin, a Ca2+-activated Cl- channel, is involved in the regulation of membrane potential in mammals. However, it remains uncertain whether Cl- channels like anoctamin regulate Paramecium behavior. Herein, replacement of external Cl- ions with acetate ion and application of Cl- channel blocker niflumic acid (NFA, 0.1 µM) increased spontaneous avoiding reactions (sARs). Hence, we hypothesized that anoctamin is involved in the stabilization of membrane potential fluctuation. Paramecium cells in which the anoctamin-like protein 1 gene was knocked down displayed frequent sARs in the culture medium without external stimulation. Treatment of anoctamin-like protein 1-knockdown cells with the Ca2+ chelator BAPTA or Ca-channel blocker nicardipine reversed the increase in sARs. Electrophysiological experiments revealed extension of membrane depolarization when positive currents were applied to anoctamin-like protein 1-knockdown cells. We concluded that anoctamin-like protein 1 works as a Cl-channel and stabilizes the membrane potential oscillation, reducing sARs.
Asunto(s)
Potenciales de la Membrana , Paramecium , Proteínas Protozoarias , Paramecium/fisiología , Paramecium/genética , Potenciales de la Membrana/efectos de los fármacos , Proteínas Protozoarias/genética , Proteínas Protozoarias/metabolismo , Canales de Cloruro/metabolismo , Canales de Cloruro/genética , Calcio/metabolismo , Ácido Niflúmico/farmacología , Técnicas de Silenciamiento del GenRESUMEN
BACKGROUND: It has not been established whether off-pump coronary artery bypass grafting (OPCABG) is less invasive than conventional CABG. In our experience, OPCABG has several advantages such as shorter operative duration, decreased requirement of blood transfusion and myocardial protection compared with conventional CABG. However, frequency of postoperative paroxysmal atrial fibrillation (PAF) is similar between these techniques and early postoperative C-reactive protein (CRP) levels have been shown to be significantly higher in OPCABG. We hypothesized that preoperative steroid administration, routinely used only in conventional CABG, may alleviate high postoperative PAF and CRP levels. Therefore, a prospective, double-blind, clinical trial was conducted in OPCABG patients to investigate the clinical effects of preoperative steroid administration. METHODS: Thirty OPCABG patients were randomly divided into 2 groups: control (Group C: n = 15) and methylprednisolone (Group M: n = 15) groups. Group M patients were intravenously administered 1000 mg methylprednisolone during anesthesia induction. RESULTS: Hospital death and infectious complication such as mediastinitis were not observed in either group. Postoperative PAF occurred in 47 % (7/15) of patients in group C but in only 1 patient in group M (7 %, P = 0.013). Early postoperative CRP levels were significantly lower in group M than in group C (peak values on postoperative day 2: group M 15 ± 6 mg/dL vs. group C 23 ± 4 mg/dL; P = 0.0002). CONCLUSIONS: Preoperative steroid administration in OPCABG patients significantly suppresses CRP elevation and prevents postoperative PAF without increasing in-hospital mortality or infectious complications.