吳造中2006-07-262018-07-112006-07-262018-07-112000http://ntur.lib.ntu.edu.tw//handle/246246/23464本研究計劃乃比較由正常血脂或高膽固醇血症兔子分離出的單一心肌細胞，在接受電刺激時其動作 電位，鉀離子流，及鈣離子流的變化，藉以探討血脂異常所造成的心臟電氣-機械功能失全的基礎細胞生 理機轉。 實驗結果發現高膽固醇血症兔子的心肌細胞較(162+8.2 pF (n=118) vs. 108+8.2 pF (n=125), p<0.05)，動作電位的零期去極化較慢 (80.7+16.2 V/s vs. 54.8+32.1 V/s, p<0.02)，及動作電位期間較長 (APD: 206.2+77.7 vs. 137.6+74.7 ms, APD90: 196.9+79.0 vs. 135.0+70.5 ms, APD50: 173.2+82.2 vs. 112.5+68.9 ms, p 值均<0.05)。高膽固醇血症兔子的心肌細胞具有較大的I Ca 離子流，然而由於其心 肌細胞較大，故I Ca 離子流密度兩者間並無顯著之差異。Ito 離子流兩者間並無顯著之差異，然因高膽固 醇血症兔子的肌細胞較大，故其心肌細胞具有較小的Ito 離子流密度。總結而論，高膽固醇血症所引起 的心肌細胞動作電位的變化，乃由其具有較小的Ito 與I Na 離子流密度。In this study project, single ventricular myocytes isolated from hyper- & normocholesterolemic rabbits were used to define the amplitude and duration of action potential in hypercholesterolemic status and to study the hyperlipidemic effect on the magnitude of calcium inward and potassium outward currents, which are two major currents responsible for the duration of action potential. The cell capacitance was 108+8.2 pF in normolipidemic myocytes (n=125) and 162+8.2 pF (n=118) in hypercholesterolemic cells (p<0.05). There were no significant difference of the resting membrane potential (-70.4+9.4 vs. –73.4+12.3 mV, p=NS) and the amplitude of action potential (115.2+24.1 vs. 13.2+16.7 mV, p=NS) between the hypercholesterolemic myocytes (n=18) and normal controls (n=11). However, the phase 0 depolarization of action potential was slower (54.8+32.1 vs. 80.7+16.2 V/s, p<0.02) and the action potential duration was longer (APD: 206.2+77.7 vs. 137.6+74.7 ms, APD90: 196.9+79.0 vs. 135.0+70.5 ms, and APD50: 173.2+82.2 vs. 112.5+68.9 ms, respectively, p<0.05). While the peak I Ca was larger in the hypercholesterolemic myocytes, capacitative surface area was also larger; thus there were no differences in the peak current densities between these two groups. While there was no difference in the peak currents, Ito density was significantly smaller in the hypercholesterolemic myocytes. In conclusion, the findings of the present experiments suggested that hypercholesterolemia associated changes in action potential resulted from the decrease in I Na and Ito density.application/pdf40943 bytesapplication/pdfzh-TW國立臺灣大學醫學院內科血脂異常電氣-機械功能動作電位鈣離子孔道鉀離子孔道DyslipidemiaElectromechanical functionAction potentialCalcium channelPotassium channelIntracellular calciumreporthttp://ntur.lib.ntu.edu.tw/bitstream/246246/23464/1/892314B002118.pdf