Ionic mechanisms underlying spontaneous muscle contractions in the liver fluke,Fasciola hepatica
| Autor: | I. Fairweather, J. G. McGeown, M. K. Graham |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
medicine.medical_specialty
Nifedipine Physiology chemistry.chemical_element In Vitro Techniques Sodium Chloride Calcium Cadmium chloride Calcium Chloride chemistry.chemical_compound Physiology (medical) Internal medicine Cyclic AMP medicine Extracellular Animals Fasciola hepatica Ions biology Ryanodine Ryanodine receptor Muscles Intracellular Membranes Liver fluke Calcium Channel Blockers biology.organism_classification Endocrinology chemistry medicine.symptom Extracellular Space Muscle Contraction Muscle contraction medicine.drug |
| Zdroj: | American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 277:R374-R383 |
| ISSN: | 1522-1490 0363-6119 |
| DOI: | 10.1152/ajpregu.1999.277.2.r374 |
| Popis: | Spontaneous contractions of liver fluke muscle were abolished in Ca2+-free saline and by 100 μM nifedipine and reduced by 5 mM cadmium chloride, suggesting that they are dependent on extracellular Ca2+. Caffeine (5 mM) significantly increased contraction amplitude and frequency. Ryanodine (100 μM) failed to block the caffeine response but significantly reduced spontaneous contraction frequency, suggesting that intracellular stores have a functional role. Cyclopiazonic acid (5 μM) had no effect on the caffeine response or spontaneous activity. 3-Isobutyl-1-methylxanthine (IBMX), forskolin, and 8-bromoadenosine 3′,5′-cyclic monophosphate significantly increased spontaneous contractions, which implies that cAMP has a regulatory function in motility. Caffeine, however, produced no measurable increase in cAMP. The caffeine effect was inhibited by cadmium chloride and nifedipine, whereas IBMX-induced increases in amplitude were reduced by cadmium chloride. Thus caffeine and cAMP appear capable of opening plasma membrane Ca2+channels, but the involvement of cAMP in caffeine responses has not been proved. |
| Databáze: | OpenAIRE |
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