Abstract
1. Ca 2+-antagonists counteract the muscular activity of the sea urchin pluteus. Agents that block rapid Na +-channels have no effect. 2. High muscular activity is induced by increasing the sea water concentration of Ca 2+ or K + and by a Ca 2+-ionophore. The stimulatory effects tend to decline. 3. Muscarinic agents counteract the effects of Ca 2+ and K +. 4. Variation in the concentration of Ca 2+ or K + has profound effects on the response to nicotinic agents. 5. It is suggested that Ca 2+ plays the role as a charge-carrier and in the release of monoamines from an inner source, and that an excessive Ca 2+-influx induces an outflux of K + leading to hyperpolarization and abolition of the impulse activity.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Comparative Biochemistry and Physiology. Part C, Comparative Pharmacology
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
