Abstract
1. 1. Contractions evoked by acetylcholine or by tetanic stimulation differed from caffeine contractures, in muscle strips isolated from the longitudinal muscle bands of the body wall of Isostichopus badionotus (Selenka), an aspidochirote holothurian. 2. 2. Tetanic contractions and responses to acetylcholine remained reproducible for hours in sea water or artificial sea water. 3. 3. Caffeine contractures declined rapidly during a series of repetitions, carried out in a bath medium which had a calcium content equivalent to that of sea water. 4. 4. Manganese, lathanum, and dantrolene have been used as calcium antagonists, with the objective of differentiating the calcium stores used in reproducible contractions from the calcium stores used in rapidly extinguishing contractures. 5. 5. Muscle strips were pretreated with an ionophore (X-537A) to confer reproducibility in a series of caffeine contractures, before use of calcium antagonists. 6. 6. For reproducible caffeine contractures, the order of effectiveness of calcium antagonists was lanthanum > manganese > dantrolene. The order of reversibility was manganese > dantrolene > lanthanum. 7. 7. For acetylcholine contractions, or tetanic contractions, the order of effectiveness of calcium antagonists was lanthanum > manganese and the order of reversibility was manganese > lanthanum. Dantrolene reversibility enhanced contractions.
Published Version
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 call