Abstract
Excitation-contraction (E-C) coupling was studied in the striated muscle fibres of lower chordates and invertebrates. In the agnathan Lampetra, twitches in response to electrical stimulation were unchanged after Ca2+ influx was blocked by the addition of Co2+. In the invertebrates examined (Branchiostoma, Oikopleura, Doliolum, Diphyes, Patinopecten and Sagitta), Ca2+ influx was necessary to cause a twitch. Whole-cell voltage clamp on muscle fibres of Lampetra revealed that intramembrane charge movement was partly blocked by 5 μM nifedipine, a dihydropyridine (DHP) derivative. Charge movement in fibres from Branchiostoma and Patinopecten was insensitive to nifedipine, although the Ca2+ current was 75% blocked by 5 μM nifedipine. The results suggest that the vertebrate type of E-C coupling was acquired between cephalochordates and agnathans, and was accompanied by the appearance of the DHP-sensitive component of intramembrane charge movement.
Original language | English |
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Pages (from-to) | 181-187 |
Number of pages | 7 |
Journal | Proceedings of the Royal Society B: Biological Sciences |
Volume | 255 |
Issue number | 1343 |
DOIs | |
Publication status | Published - 22 Feb 1994 |
ASJC Scopus subject areas
- General Biochemistry,Genetics and Molecular Biology
- General Immunology and Microbiology
- General Environmental Science
- General Agricultural and Biological Sciences