caa a22 4500 465826288 CHVBK 20180323112150.0 cr unu---uuuuu 170327e19901101xx s 000 0 eng 10.1007/BF00691717 doi (NATIONALLICENCE)springer-10.1007/BF00691717 Diversity of mechanical responses and their possible underlying mechanisms in the proboscis muscles of Busycon canaliculatum [Elektronische Daten] [H. Huddart, D. Brooks, R. Hill, R. Lennard] Summary: Mechanical responses of the radular protractor and retractor, the odontophore retractor and the radular sac muscles ofBusycon canaliculatum were compared. The radular protractor responded to both ACh and high K salines with similar slow, smooth contractures showing no evidence of fast twitch activity. The radular sac, odontophore retractor, and radular retractor muscles responded to low K salines with bursts of fast twitches at a mechanical threshold below that for responses in the radular protractor. With high K salines these three muscles showed inactivation of fast twitch activity and replacement by slow maintained tonic force. With rare exceptions, the ACh responses of all four muscles consisted of slow, maintained tonic contractures with no fast twitch activity, although individual muscles differed in their ACh sensitivity. A scheme is presented to explain the mechanical modus operandi of this complex organ by the co-operative actions of these four physiologically diverse muscles. It is proposed that fast twitch responses depend upon the activity of fast transient Ca channels showing strong voltage sensitivity and ready voltage inactivation. It is proposed that maintained tonic contractures in all the muscles depends upon the activity of slow long-lasting voltage-dependent Ca channels which only open with substantial membrane depolarization. It is suggested that K-induced and ACh-induced responses may activate a similar cellular Ca pool but by different membrane transduction routes. Springer-Verlag, 1990 Busycon canaliculatum nationallicence Proboscis muscles nationallicence K-induced responses nationallicence ACh-induced responses nationallicence Calcium dependency nationallicence Huddart H. Department of Zoology, The University of Rhode Island, Biological Sciences Building, 02881, Kingston, Rhode Island, USA aut Brooks D. Department of Zoology, The University of Rhode Island, Biological Sciences Building, 02881, Kingston, Rhode Island, USA aut Hill R. Department of Zoology, The University of Rhode Island, Biological Sciences Building, 02881, Kingston, Rhode Island, USA aut Lennard R. Department of Zoology, The University of Rhode Island, Biological Sciences Building, 02881, Kingston, Rhode Island, USA aut Journal of Comparative Physiology B Springer-Verlag 159/6(1990-11-01), 717-725 0174-1578 159:6<717 1990 159 360 https://doi.org/10.1007/BF00691717 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00691717 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Huddart H. Department of Zoology, The University of Rhode Island, Biological Sciences Building, 02881, Kingston, Rhode Island, USA aut NATIONALLICENCE 700 1- Brooks D. Department of Zoology, The University of Rhode Island, Biological Sciences Building, 02881, Kingston, Rhode Island, USA aut NATIONALLICENCE 700 1- Hill R. Department of Zoology, The University of Rhode Island, Biological Sciences Building, 02881, Kingston, Rhode Island, USA aut NATIONALLICENCE 700 1- Lennard R. Department of Zoology, The University of Rhode Island, Biological Sciences Building, 02881, Kingston, Rhode Island, USA aut NATIONALLICENCE 773 0- Journal of Comparative Physiology B Springer-Verlag 159/6(1990-11-01), 717-725 0174-1578 159:6<717 1990 159 360 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer