San Andrés M D, López C, Encinas T, González F, San Andrés M I, Rodríguez C
Cátedra de Farmacología, Facultad de Veterinaria, Universidad Complutense de Madrid, Spain.
Zentralbl Veterinarmed A. 1993 Nov-Dec;40(9-10):749-56. doi: 10.1111/j.1439-0442.1993.tb00692.x.
The effects of verapamil and sodium nitroprusside on smooth muscle strips from the floor of the reticular groove of adult cattle were studied. The mechanical activity of the muscle strips was recorded isometrically. Depolarization was induced with cumulative KCl concentrations (8.8-42.4 mmol/l) in Tyrode solution. This response was extracellular Ca2+ dependent. Verapamil and sodium nitroprusside caused a concentration dependent reduction of the KCl-induced contraction of the reticular groove muscle preparations; their IC50 were 3.9 x 10(-6) mol/l and 1.4 x 10(-4) mol/l, respectively. Pre-incubation with both antagonists (30 min) before KCl addition showed that sodium nitroprusside (10(-6) mol/l) did not affect, but verapamil (10(-6) mol/l) inhibited the KCl response of the muscle preparations. CaCl2 caused a concentration dependent (0.25-7 mmol/l) contraction of the KCl-depolarized muscle strips. Pre-incubation with verapamil (10(-6) mol/l) and sodium nitroprusside (10(-6) mol/l) before CaCl2 addition inhibited the response for about 80% and 20% respectively. These results indicate that action of verapamil may be related to voltage-dependent channel blockade. However, the nitroprusside action could not be completely attributed to these channels.
研究了维拉帕米和硝普钠对成年牛网状沟底部平滑肌条的影响。肌肉条的机械活动采用等长记录法。在台氏液中用累积的氯化钾浓度（8.8 - 42.4 mmol/L）诱导去极化。这种反应依赖于细胞外钙离子。维拉帕米和硝普钠使网状沟肌肉制剂的氯化钾诱导收缩呈浓度依赖性降低；它们的半数抑制浓度（IC50）分别为3.9×10⁻⁶ mol/L和1.4×10⁻⁴ mol/L。在添加氯化钾前用两种拮抗剂预孵育（30分钟）表明，硝普钠（10⁻⁶ mol/L）不影响，但维拉帕米（10⁻⁶ mol/L）抑制肌肉制剂的氯化钾反应。氯化钙使氯化钾去极化的肌肉条产生浓度依赖性（0.25 - 7 mmol/L）收缩。在添加氯化钙前用维拉帕米（10⁻⁶ mol/L）和硝普钠（10⁻⁶ mol/L）预孵育分别抑制反应约80%和20%。这些结果表明，维拉帕米的作用可能与电压依赖性通道阻断有关。然而，硝普钠的作用不能完全归因于这些通道。
