CARDIAC MUSCLE PROPERTIES IN SENESCENT RATS IS NOT RELATED TO SERUM UREA LEVELS

心血管系统最显著的变化之一， 伴随着年龄的增长， 心脏收缩。 这种与年龄相关的延长发生在男性，较低 哺乳动物和啮齿动物，显然代表了年龄相关的 不同物种心肌的变化。 然而，随着年龄的增长 在啮齿类动物中也常常伴随着 肾功能，使其难以划分心血管 完全与年龄相关的变化与肾脏相关的下降。 在 以确定心肌功能是否在衰老（24个月） 雄性Wistar大鼠随太阳光的变化，测定离体海马神经元的功能， 高SUN和低SUN动物的心肌。 肌肉 在正常林格氏碳酸氢盐溶液（（Ca）= 1.0 mM）中浸泡 并在30 ℃下以Lmax刺激收缩24 min-1。 的 平均± SEM、SUN、静息张力（RT）、发生性抽搐 张力（TT）、最大张力上升速率（dt/dt max）和 收缩持续时间（CD）。

One of the most striking changes in the cardiovascular system which accompanies advancing age is the prolongation of the duration of systole. This age-associated prolongation occurs in man, lower mammals, and in rodents, and apparently represents an age related change in cardiac muscle across species. However, advancing age in rodents is also often accompanied by a progressive decline in renal function, making it difficult to partition cardiovascular changes into fully age-related versus renal related declines. In order to determine whether myocardial function in senescent (24 mo) male Wistar rats varies with SUN, we measured function of isolated cardiac muscle from animals with higher and lower SUN. Muscles were bathed in normal Ringer's bicarbonate solution ((Ca) = 1.0 mM) and stimulated to contract 24 min-1 at 30 degree C at Lmax. The mean plus/minus SEM, SUN, resting tension (RT), developed twitch tension (TT), maximum rate of tension rise (dt/dt max) and contraction duration (CD) in the two groups.