CILIARY BEATING OF SCHISTOSOMA MIRACIDIUM-POSSIBLE INVOLVEMENT OF CYCLIC NCLEOTIDE AND ION CHANNEL

草履虫纤毛运动调控的研究促使我们进一步探讨毛蚴纤毛运动的调控机制。本研究旨在探讨cAMP、cGMP、蛋白激酶A和离子通道在血吸虫毛蚴纤毛搏动信号转导机制中的可能作用。毛蚴在1%NaCl溶液中停止游动。加入膜透性cAMP或cGMP可使约40%毛蚴在高渗透压下游动，但游动速度约为在水中游动毛蚴的1/6。此外，福斯可林，腺苷酸环化酶和鸟苷酸环化酶的激活剂，和IBMX，磷酸二酯酶的抑制剂也引起毛蚴向前游泳。这些试剂的作用呈剂量依赖性，霍乱毒素通过对G蛋白的作用而提高后生动物腺苷酸环化酶的活性。霍乱毒素对毛蚴纤毛搏动无影响。蛋白激酶A抑制剂H88和H89抑制毛蚴在水中的游动。K^+通道阻断剂奎宁和α-dendrotixin可使毛蚴在水中游动。H88、H89、奎宁和α树毒素的抑制作用呈剂量依赖性。Na^+通道阻断剂和Ca^+通道阻断剂对毛蚴的游动无影响，提示环核苷酸、蛋白激酶A和K^+通道对毛蚴纤毛运动有调节作用。

The studies on regulation of ciliary motility in Paramecium encouraged us to investigate the control mechanisms of ciliary beat of schistosome miracidia. The present study aimed at investigating the possible involvement of cAMP,cGMP,protein kinase A and ion channels in signal transduction mechanisms of ciliary beat of schistosome miracidia.Schistosome miracidia swim in water by means of numerous cilia which cover the body surface. The miracidia stop swimming in 1% NaCL solution. Addition of membrane permeable cAMP or cGMP causes about 40% of miracidia to swim under high osmotic pressure, the swimming speed is about 1/6 of that of miracidia swimming in water though. Addition of forskolin, an activator of adenyl cyclase and guanyl cyclase, and IBMX,an inhibitor or phosphodiesterase also caused miracidial forward swimming. The effect of these reagents was dose dependent.Cholera toxin increases adenyl cyclase activity of metazoan via tis effect on G-protein. However, cholera toxin did not have any effect on ciliary beat of miracidia. Inhibitor of protein kinase A,H88 and H89, inhibited miracidial swimming in water. K^+channel blocker, quinine and alpha dendrotixin, caused swimming of miracidia in water. Inhibitory effect of H88, H89, quinine and alpha dendrotoxin was dose dependent. Na^+channel blocker and Ca^<++>channel blocker did not have any effect on swimming of miracidia.These results suggest that cyclic nucleotide, protein kinase A and K^+channel regulate ciliary beat of schistosome miracidia.