Spontaneous release of nitric oxide inhibits electrical, Ca2+ and mechanical transients in canine gastric smooth muscle.
Spontaneous release of nitric oxide inhibits electrical, Ca2+ and mechanical transients in canine gastric smooth muscle.
复制标题
一氧化氮的自发释放抑制犬胃平滑肌的电瞬变、Ca2+ 瞬变和机械瞬变。
DOI：
10.1113/jphysiol.1992.sp018921
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Sanders,KM
中科院分区：
文献类型：
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作者：
Ozaki,H;Blondfield,DP;Hori,M;Publicover,NG;Kato,I;Sanders,KM
1.在犬胃窦，节律性电活动包括一个快速上升相，随后是一个平台去极化。响应慢波，胞浆Ca 2+（[Ca 2 +]cyt）和张力增加。2.硝普钠（SNP，0.5 μ M）的加入降低了慢波的平台相的振幅，而对上行程去极化没有显着影响。SNP还抑制与平台电位相关的[Ca 2 +]cyt和张力的变化。SNP在高于0.1 μ M的浓度下诱导负性变时效应。3.与SNP的作用类似，在慢波期间用紫外线（UV）光照射肌肉引起过早复极。已知UV照射在一些组织中释放NO。4. L-NG-单甲基精氨酸（L-NMMA，300 μ M）、亚甲蓝（MB，5 μ M）和氧合血红蛋白（oxy-Hb，5 μ M）增加收缩力。相反，L-精氨酸（L-Arg，300 μ M）降低收缩力并拮抗L-NMMA的作用。5.在上行期，SNP引起[Ca 2 +]cyt的小幅度降低和力的大幅度降低，表明SNP引起Ca 2+敏感性降低。6.在α毒素渗透的肌肉中，环GMP（100 μ M）和紫外线照射抑制Ca（2+）诱导的收缩（pCa 5.5）。7.这些数据表明，NO或NO相关化合物在胃肌肉中自发释放。这些药物对兴奋-收缩偶联有两种作用：（i）（直接和/或间接）抑制参与慢波平台期的电压依赖性Ca 2+通道，（ii）降低收缩元件的Ca 2+敏感性。
1. In canine antrum, rhythmic electrical activity consists of a rapid upstroke phase followed by a plateau depolarization. In response to slow waves, cytosolic Ca2+ ([Ca2+]cyt) and tension increased. 2. Addition of sodium nitroprusside (SNP, 0.5 microM) decreased the amplitude of the plateau phase of slow waves without significant effects on the upstroke depolarization. SNP also inhibited changes in [Ca2+]cyt and tension associated with the plateau potential. SNP induced a negative chronotropic effect at concentrations above 0.1 microM. 3. Similar to the effects of SNP, illumination of muscles during slow waves with ultraviolet (UV) light caused premature repolarization. UV illumination is known to release NO in some tissues. 4. L‐NG‐monomethyl‐arginine (L‐NMMA, 300 microM), Methylene Blue (MB, 5 microM) and oxyhaemoglobin (oxy‐Hb, 5 microM) increased the force of contractions. In contrast, L‐arginine (L‐Arg, 300 microM) decreased contractile force and antagonized the effects of L‐NMMA. 5. During the upstroke phase, SNP caused a small reduction in [Ca2+]cyt and a large reduction in force, suggesting that SNP caused a decrease in Ca2+ sensitivity. 6. In muscles permeabilized by alpha‐toxin, cyclic GMP (100 microM) and UV illumination inhibited Ca(2+)‐induced contraction (at pCa 5.5). 7. These data suggest that NO or NO‐related compounds are spontaneously released in gastric muscles. These agents have two effects on excitation‐contraction coupling: (i) inhibition (directly and/or indirectly) of the voltage‐dependent Ca2+ channels that participate in the plateau phase of slow waves, and (ii) reduction in the Ca2+ sensitivity of the contractile element.