The superficial buffer barrier in vascular smooth muscle
| Autor: | Cannell M, van Breemen C, Chen Q |
|---|---|
| Rok vydání: | 1992 |
| Předmět: |
Male
Myofilament Thapsigargin Vascular smooth muscle Fura-2 Physiology Vena Cava Inferior Calcium-Transporting ATPases In Vitro Techniques Inferior vena cava Muscle Smooth Vascular chemistry.chemical_compound Caffeine Physiology (medical) medicine Animals Pharmacology Terpenes Chemistry Calcium Radioisotopes Endoplasmic reticulum General Medicine Sarcoplasmic Reticulum medicine.vein Biochemistry Biophysics Calcium Rabbits medicine.symptom Muscle Contraction Muscle contraction |
| Zdroj: | Canadian Journal of Physiology and Pharmacology. 70:509-514 |
| ISSN: | 1205-7541 0008-4212 |
| DOI: | 10.1139/y92-066 |
| Popis: | Force development and fura-2 fluorescence were simultaneously measured in the rabbit inferior vena cava. Discharging SR Ca2+ with either caffeine or norepinephrine prior to stimulation of Ca2+ influx induced a delay of 30–70 s between the intracellular Ca2+ signal and development of force. This delay was abolished by the application of caffeine. These data support the superficial buffer barrier hypothesis, which holds that Ca2+ entry from the extracellular space proceeds via a restricted cytoplasmic region between the inner plasmalemmal surface and the peripheral sarcoplasmic reticulum (SR). Ca2+ accumulation by this SR fraction appears to be able to delay Ca2+ entry into the deeper myoplasm where it activates the myofilaments. Caffeine and thapsigargin elevated the steady-state [Ca2+]i, suggesting a contribution by the SR Ca2+ pump to Ca2+ extrusion from the cells. Norepinephrine enhanced myofilament Ca2+ sensitivity, while caffeine decreased it.Key words: smooth muscle, superficial buffer barrier, Ca2+ entry, Ca2+ extrusion, fura-2 fluorescence. |
| Databáze: | OpenAIRE |
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