Gende O A, Camilión De Hurtado M C
Centro de Investigaciones Cardiovasculares, Faculdad de Ciencias Médicas, Universidad Nacional de La Plata, Argentina.
Arch Int Physiol Biochim. 1987 Sep;95(3):183-8.
The changes in spontaneous rate of isolated rat atria in response to increased extracellular osmotic pressure were examined using sucrose, urea and several polyhydroxyalcohols (mannitol, glycerol and ethylene glycol) as test solutes. Sucrose, mannitol and urea induced a fall in atrial rate, which was transient with the last compound. On the other hand, media made hyperosomotic by addition of glycerol or ethylene glycol increased the beating frequency. Sucrose effect was not affected by low extracellular calcium, nifedipine or atropine. Glycerol-induced increase in atrial rate was a calcium-dependent mechanism sensitive to nifedipine. Thus, positive chronotropic effect occurs in the rat atria only with certain diffusible solutes which probably promote calcium entry. The response to pure osmotic change, resulting from changes in concentration of ions within the cell as water moves out, is a negative chronotropic effect.
使用蔗糖、尿素和几种多元醇（甘露醇、甘油和乙二醇）作为测试溶质，研究了离体大鼠心房自发率对细胞外渗透压升高的反应变化。蔗糖、甘露醇和尿素会导致心房率下降，其中尿素引起的下降是短暂的。另一方面，添加甘油或乙二醇使培养基渗透压升高会增加搏动频率。蔗糖的作用不受低细胞外钙、硝苯地平或阿托品的影响。甘油引起的心房率增加是一种对硝苯地平敏感的钙依赖性机制。因此，只有某些可能促进钙内流的可扩散溶质才会在大鼠心房中产生正性变时作用。由于水流出时细胞内离子浓度变化导致的纯渗透压变化的反应是负性变时作用。
