Asunto(s)
Autoinmunidad , Enteropatías Perdedoras de Proteínas/inmunología , Adulto , Femenino , HumanosAsunto(s)
Glomerulonefritis/complicaciones , Hemorragia/complicaciones , Enfermedades Pulmonares/complicaciones , Anciano , Esquema de Medicación , Femenino , Glomerulonefritis/tratamiento farmacológico , Glomerulonefritis/patología , Humanos , Masculino , Metilprednisolona/administración & dosificación , Persona de Mediana EdadRESUMEN
1. The dependence on pH of inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ release was studied in saponin-skinned smooth muscle cells from guinea-pig portal vein, using the indicator fura-2 to monitor Ca2+ release. 2. Increasing pH between 6.7 and 7.3 enhanced the rate of IP3-induced Ca2+ release at all the Ca2+ concentrations above 30 nM without changing the bell-shaped dependence of the Ca2+ release rate on Ca2+ concentration with a peak near 300 nM. 3. The ascending limb of the biphasic Ca2+ dependence was shifted slightly toward the lower Ca2+ concentration at pH 7.3, suggesting an increase in the Ca2+ sensitivity of IP3-induced Ca2+ release at the higher pH. 4. With the elevation in pH from 6.7 to 7.3 at 100 nM Ca2+, about 7-fold higher IP3 concentration was required to release half of the Ca2+ in the store within 15 s. This pH-dependent change in the IP3 sensitivity was smaller at 1 microM Ca2+ and was indiscernible in the absence of Ca2+. 5. These results suggest that H+ may inhibit binding of IP3 and Ca2+ to the modulator sites of the Ca2+ release mechanism. However, these effects on the binding sites may not fully explain the complex effect of pH, and there may be pH-dependent step(s) involved in the gating mechanism of IP3 channels. The present study demonstrates the importance of pH as a modulator of IP3-induced Ca2+ release.
Asunto(s)
Calcio/metabolismo , Concentración de Iones de Hidrógeno , Inositol 1,4,5-Trifosfato/farmacología , Músculo Liso Vascular/metabolismo , Animales , Permeabilidad de la Membrana Celular , Relación Dosis-Respuesta a Droga , Cobayas , Músculo Liso Vascular/citología , Concentración Osmolar , Factores de TiempoRESUMEN
Inositol 1,4,5-trisphosphate (InsP3)-induced Ca2+ release depends on the cytoplasmic concentration of Ca2+ in a biphasic manner: activated with the increase in Ca2+ up to approximately 300 nM and inhibited by its further increase. Kinetic studies of the Ca2+ release with rapid increase in Ca2+ or InsP3 using respective caged compounds indicated that the effects of Ca2+ appear immediately upon change in the Ca2+ concentration. Recovery from the Ca(2+)-dependent inhibition seemed also rapid after reduction in the Ca2+ concentration. These results indicate that there is a Ca(2+)-mediated positive feedback control of InsP3-induced Ca2+ release below 300 nM Ca2+. This feedback control seems to explain, at least partly, the phenomenon that InsP3 is more effective in the Ca2+ stores with greater Ca2+ loading. The Ca(2+)-mediated feedback control is also expected to give rise to temporally or spatially confined Ca2+ release as well as Ca2+ wave within the cells.
Asunto(s)
Calcio/metabolismo , Inositol 1,4,5-Trifosfato/metabolismo , Transducción de Señal/fisiología , Animales , Calcio/farmacología , Retroalimentación , Inositol 1,4,5-Trifosfato/farmacologíaAsunto(s)
Ferredoxinas/aislamiento & purificación , Mycobacterium/análisis , Cristalización , Estabilidad de Medicamentos , Espectroscopía de Resonancia por Spin del Electrón , Ferredoxinas/metabolismo , Concentración de Iones de Hidrógeno , Hierro/análisis , Peso Molecular , Oxidación-Reducción , Azufre/análisisRESUMEN
Computed tomographic feature of uterine carcinoma were described based on our own experience of 40 cases (cervix 35, body 5) and on the review of the recent articles. It was found to be not always possible to detect tumor infiltration not only at the cervix but lateral extension to the parametrium on CT. CT was quite effective, however, the diagnosis of iliac-paraaortic lymph node metastasis and invasion into the bladder and/or the rectum. Increased fibrous tissue and perirectal fat were the commonest postirradiation changes seen on CT. CT was the only measure to clarify surgical complication in some cases.