Kibble A V, Burgoyne R D
The Physiological Laboratory, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK.
Pflugers Arch. 1996 Jan;431(3):464-6. doi: 10.1007/BF02207288.
The effect of calmodulin on exocytosis in bovine adrenal medullary chromaffin cells was examined by the use of patch-clamp capacitance recording. Calmodulin was dialysed into cells via the patch-pipette and cells stimulated by depolarisation. Following a test stimulation, cells were dialysed with a control or with a calmodulin containing buffer for 10 mins and then were stimulated at 2 min intervals thereafter. The inclusion of calmodulin in the pipette did not increase Ca2+ currents which instead decreased during dialysis. The presence of calmodulin, however, resulted in a 2-fold increase in the initial rate of exocytosis during the 10 min depolarisation step. These results demonstrate the utility of the patch-clamp capacitance technique for the examination of the effect of soluble proteins on exocytosis and in conjunction with previous work on permeabilised chromaffin cells suggest that calmodulin regulates late steps in Ca2+-dependent exocytosis.
利用膜片钳电容记录技术研究了钙调蛋白对牛肾上腺髓质嗜铬细胞胞吐作用的影响。通过膜片微电极将钙调蛋白透析到细胞中，然后通过去极化刺激细胞。在一次测试刺激后，用对照缓冲液或含钙调蛋白的缓冲液对细胞进行10分钟的透析，之后每隔2分钟刺激一次。微电极中加入钙调蛋白不会增加Ca2+电流，相反，在透析过程中Ca2+电流会降低。然而，钙调蛋白的存在导致在10分钟的去极化步骤中胞吐作用的初始速率增加了两倍。这些结果证明了膜片钳电容技术在研究可溶性蛋白对胞吐作用影响方面的实用性，并且结合之前对透化嗜铬细胞的研究表明，钙调蛋白调节Ca2+依赖性胞吐作用的后期步骤。
