Ponce-Monter H, Villaneuva T, Ortega B G, Campos M G
Unidad de Investigación Médica en Farmacología, Hospital de Especialidades, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, México, D.F.
Arch Med Res. 1995;26 Spec No:S185-8.
The effect of ortho-vanadate on Ca(2+)-influx in the uterine smooth muscle was investigated. Orthovanadate (10-300 microM) gradually increased the muscular tone of rat isolated uterus bathed in a high K+ (30 mM)-low Ca2+ (0.15 mM) solution. This response was blocked by nifedipine (10 nM) and reproduced by BAY K 8644 (3-300 nM). Atropine and indomethacin were unable to block the effects induced by vanadate and BAY K 8644. Cumulative addition of CaCl2 to the tissue bathed in a depolarized solution without CaCl2 produced a graded tonic response that was potentiated by either vanadate (30 microM) or BAY K 8644 (30 nM), and inhibited by nifedipine. Neither vanadate (30 microM) nor BAY K 8644 (30 nM) modified the uterine tone of tissues immersed in the depolarizing solution without CaCl2. It is concluded that vanadate-induced contraction of rat uterine smooth muscle involves Ca(2+)-influx from the extracellular medium to the myometrial cell. Vanadate might act as a Ca(2+)-channel activator, similar to BAY K8644.
研究了原钒酸盐对子宫平滑肌中钙离子内流的影响。原钒酸盐（10 - 300微摩尔）可逐渐增强浸泡在高钾（30毫摩尔）-低钙（0.15毫摩尔）溶液中的大鼠离体子宫的肌张力。这种反应可被硝苯地平（10纳摩尔）阻断，并可被BAY K 8644（3 - 300纳摩尔）重现。阿托品和吲哚美辛无法阻断钒酸盐和BAY K 8644诱导的效应。在无氯化钙的去极化溶液中向组织累积添加氯化钙会产生分级的强直反应，该反应可被钒酸盐（30微摩尔）或BAY K 8644（30纳摩尔）增强，并被硝苯地平抑制。钒酸盐（30微摩尔）和BAY K 8644（30纳摩尔）均未改变浸泡在无氯化钙的去极化溶液中的组织的子宫肌张力。结论是，钒酸盐诱导的大鼠子宫平滑肌收缩涉及钙离子从细胞外介质流入肌层细胞。钒酸盐可能作为一种钙离子通道激活剂，类似于BAY K8644。
