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

1996 Fiscal Year Final Research Report Summary

• Project/Area Number: 07670285
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 寄生虫学(含医用動物学)
• Research Institution: NAGASAKI UNIVERSITY
• Principal Investigator: AOKI Yoshiki INSTITUTE OF TROPICAL MEDICINE PROFESSOR, 熱帯医学研究所, 教授 (90039925)
• Co-Investigator(Kenkyū-buntansha): MITSUI Yoshinori INSTITUTE OF TROPICAL MEDICINE RESEARCH ASSOCIATE, 熱帯医学研究所, 助手 (50229738) ; FUJIMAKI Yasunori INSTITUTE OF TROPICAL MEDICINE ASSISTANT PROFESSOR, 熱帯医学研究所, 講師 (10209083) ; NIWA Masami SCHOOL OF MEDICINE PROFESSOR, 医学部, 教授 (20136641)
• Project Period (FY): 1995 – 1996
• Keywords: schistosome / miracidia / cilia / cAMP / cGMP / protein kinase A / K^+channel

Research Abstract

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.