Bazán-Perkins B, Carbajal V, Sommer B, Macías-Silva M, Gonzalez-Martinez M, Valenzuela F, Daniel E E, Montaño L M
Departamento de Farmacología, Facultad de Medicina, UNAM, México DF, México.
Naunyn Schmiedebergs Arch Pharmacol. 1998 Nov;358(5):567-73. doi: 10.1007/pl00005294.
We evaluated the role of protein kinase C (PKC) in the sustained bronchial contraction (SBC) induced by carbachol (Cch) or histamine in a Ca2+-free medium and the possibility that each agonist uses a different Ca2+ store for this response. We studied third-order bronchi and airway smooth muscle (ASM) from first-order bronchi dissected free of cartilage and epithelium. Bronchial and ASM responsiveness to Cch or histamine were evaluated in Krebs solution (2.5 mM Ca2+) and in Ca2+-free medium. Cch and histamine induced an SBC in bronchial tissues in Ca2+-free medium. In ASM each agonist produced a transient contraction, but the response to histamine was much smaller. Cch induced a concentration-dependent accumulation of inositol phosphates (IPs) in both bronchi and ASM; however, histamine did not induce significant accumulation of IPs. Repeated exposure to histamine in bronchial rings abolished contractile responses in Ca2+-free media, but Cch added afterwards still produced a sustained contraction. This response was blocked when bronchial tissues were preincubated with 10 microM cyclopiazonic acid (CPA). Brief incubation of these preparations with a high EGTA concentration (1 mM) abolished the histamine-induced SBC. The SBC induced by Cch or histamine in Ca2+-free medium was not affected by the preincubation of the tissues with calphostin C, chelerythrine or staurosporine. We concluded that Cch mobilizes Ca2+ from two different sources during the SBC in Ca2+-free medium: from a CPA-sensitive one from sarcoplasmic reticulum (SR) and from a putative extracellular membrane Ca2+ pool sensitive to 1 mM EGTA, and neither process involved PKC activation. Histamine appeared to utilize the extracellular membrane pool only.
我们评估了蛋白激酶C（PKC）在无钙培养基中由卡巴胆碱（Cch）或组胺诱导的持续性支气管收缩（SBC）中的作用，以及每种激动剂是否利用不同的钙库来产生这种反应的可能性。我们研究了从不含软骨和上皮的一级支气管中分离出的三级支气管和气道平滑肌（ASM）。在 Krebs 溶液（2.5 mM 钙）和无钙培养基中评估支气管和 ASM 对 Cch 或组胺的反应性。Cch 和组胺在无钙培养基中诱导支气管组织发生 SBC。在 ASM 中，每种激动剂都产生短暂收缩，但对组胺的反应要小得多。Cch 在支气管和 ASM 中均诱导肌醇磷酸（IPs）浓度依赖性积累；然而，组胺并未诱导 IPs 的显著积累。在无钙培养基中，支气管环反复暴露于组胺会消除收缩反应，但随后添加的 Cch 仍会产生持续性收缩。当支气管组织用 10 microM 环匹阿尼酸（CPA）预孵育时，这种反应被阻断。用高浓度 EGTA（1 mM）对这些制剂进行短暂孵育可消除组胺诱导的 SBC。在无钙培养基中，Cch 或组胺诱导的 SBC 不受组织用钙磷蛋白 C、白屈菜红碱或星形孢菌素预孵育的影响。我们得出结论，在无钙培养基中 SBC 期间，Cch 从两个不同来源动员钙：一个来自对 CPA 敏感的肌浆网（SR），另一个来自对 1 mM EGTA 敏感的假定细胞外膜钙库，且这两个过程均不涉及 PKC 激活。组胺似乎仅利用细胞外膜钙库。
