Cotter M A, Cameron N E, Robertson S
Biomedical Sciences, Marischal College, University of Aberdeen.
Exp Physiol. 1992 Nov;77(6):829-38. doi: 10.1113/expphysiol.1992.sp003649.
Contractile properties of left ventricular papillary muscles and atria from streptozotocin-diabetic and from non-diabetic rats fed a 40% galactose diet were measured in vitro. There was a characteristic slowing of twitch responses for both tissues and both treatments (P < 0.05). Time to peak contraction was prolonged by 18-33% and maximum rate of contraction was reduced by 10-17%. Relaxation was also affected, with a 13-37% increase in half-relaxation time and a 7-25% reduction in the maximum rate of relaxation. There were treatment differences between papillary muscles and left atrium, diabetes having a more marked effect on the former, whereas galactosaemia caused more pronounced changes in the latter. The resting beat rate of the right atrium was 22% reduced in diabetic and galactosaemic rats (P < 0.01). When maximally stimulated with isoprenaline, beat rate did not rise to the level of stimulated controls (P < 0.01). Papillary muscle speed-related contractile properties also showed a reduced response to isoprenaline in diabetic and galactosaemic groups compared to normal controls. The greatest deficit was found for maximum rate of relaxation where responsiveness was 41 and 34% less for diabetic and galactosaemic groups respectively (P < 0.01). Polyol pathway metabolites in diabetic ventricles were increased 8-fold. In galactosaemic rats galactitol accumulation led to a 530-fold increase in polyols. The data suggest that polyol pathway activity may be an important factor in the aetiology of contractile and chronotropic changes in diabetic and galactosaemic cardiomyopathy.
在体外测量了链脲佐菌素诱导的糖尿病大鼠以及喂食40%半乳糖饮食的非糖尿病大鼠的左心室乳头肌和心房的收缩特性。对于这两种组织和两种处理方式，抽搐反应均出现了特征性减慢（P < 0.05）。收缩峰值时间延长了18 - 33%，最大收缩速率降低了10 - 17%。舒张也受到影响，半舒张时间增加了13 - 37%，最大舒张速率降低了7 - 25%。乳头肌和左心房之间存在处理差异，糖尿病对前者的影响更为显著，而半乳糖血症对后者引起的变化更为明显。糖尿病和半乳糖血症大鼠右心房的静息心率降低了22%（P < 0.01）。用异丙肾上腺素进行最大刺激时，心率未升至受刺激对照组的水平（P < 0.01）。与正常对照组相比，糖尿病和半乳糖血症组的乳头肌速度相关收缩特性对异丙肾上腺素的反应也降低。在最大舒张速率方面发现最大缺陷，糖尿病组和半乳糖血症组的反应性分别比正常对照组低41%和34%（P < 0.01）。糖尿病心室中的多元醇途径代谢产物增加了8倍。在半乳糖血症大鼠中，半乳糖醇的积累导致多元醇增加了530倍。数据表明，多元醇途径活性可能是糖尿病和半乳糖血症性心肌病收缩和变时性变化病因中的一个重要因素。
