Pharmacological control of muscular activity in the sea urchin larva. II. Role of calcium in nicotinic stimulation and paralysis,and the modulatory role of muscarinic agents |
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| Affiliation: | 1. Associate Laboratory i4HB Institute for Health and Bioeconomy, NOVA School of Science and Technology, NOVA University of Lisbon, Caparica 2819 516, Portugal;2. UCIBIO Applied Molecular Biosciences Unit, Department of Life Sciences, NOVA School of Science and Technology, NOVA University of Lisbon, Caparica 2819 516, Portugal;3. Unit of Biochemical Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Box 210, Stockholm SE-171 77, Sweden;1. College of Life Sciences, Yan''an University, Yan''an, Shaanxi 716000, China;2. Yan''an Key Laboratory of Ecological Restoration, Yan''an, China;1. School of Public Health, Shandong Second Medical University, Weifang 261053, China;2. Key Laboratory of Maternal & Fetal Medicine of National Health Commission of China，Shandong Provincial Maternal and Child Health Care Hospital Affiliated to Qingdao University, Jinan 250014, China;3. International Center, Jinan Foreign Language School, Jinan 250108, China |
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| Abstract: | 1. Ca2+-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 Ca2+ or K+ and by a Ca2+-ionophore. The stimulatory effects tend to decline.3. Muscarinic agents counteract the effects of Ca2+ and K+.4. Variation in the concentration of Ca2+ or K+ has profound effects on the response to nicotinic agents.5. It is suggested that Ca2+ plays the role as a charge-carrier and in the release of monoamines from an inner source, and that an excessive Ca2+-influx induces an outflux of K+ leading to hyperpolarization and abolition of the impulse activity. |
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