Human airway smooth muscle in cell culture: control of the intracellular calcium store.
The release of intracellularly stored calcium (Ca2+) contributes to the rise in cytoplasmic Ca2+ concentration during agonist-induced activation of airway smooth muscle. We describe a novel preparation--human airway smooth muscle cells cultured in monolayers--which has enabled the investigation of the identity and the function of this intracellular Ca2+ store. Cells, enzymatically dispersed from surgically resected human bronchi, were cultured in monolayers and confirmed as smooth muscle by positive immunocytochemical staining for actin and myosin. The release of intracellularly stored Ca2+ in response to bronchoconstrictor agonists, histamine and carbachol, was demonstrated by stimulation of Ca2+ efflux from 45Ca-labelled cells. The technique of permeabilisation of the plasmalemmal membrane by saponin allowed the measurement of the Ca2+ content of the intracellular store in 45Ca-labelled cells. Uptake of Ca2+ by the store was energy-dependent and was enhanced by cyclic AMP. The effects of inhibitors of sarcoplasmic reticulum and mitochondrial function on Ca2+ uptake identified the store as sarcoplasmic reticulum. Inositol 1,4,5-trisphosphate released stored Ca2+ in a time and dose-dependent manner, supporting its putative role as an intracellular messenger for Ca2+ release in human airway smooth muscle.
Twort
C H
CH
Division of Medicine, United Medical School, St Thomas' Hospital, London, UK.
van Breemen
C
C
D000255:Adenosine Triphosphate / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000502:physiology; D006801:Humans; D007293:Inosine Triphosphate / Q000502:physiology; D008856:Microscopy, Fluorescence; D008931:Mitochondria, Muscle / Q000378:metabolism; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism*; D010539:Permeability; D012137:Respiratory System / Q000166:cytology / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism
D002132:Calcium Radioisotopes; D007293:Inosine Triphosphate; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D002118:Calcium