Resting calcium influx in airway smooth muscle.
Plasma membrane Ca2+ leak remains the most uncertain of the cellular Ca2+ regulation pathways. During passive Ca2+ influx in non-stimulated smooth muscle cells, basal activity of constitutive Ca2+ channels seems to be involved. In vascular smooth muscle, the 3 following Ca2+ entry pathways contribute to this phenomenon: (i) via voltage-dependent Ca2+ channels, (ii) receptor gated Ca2+ channels, and (iii) store operated Ca2+ channels, although, in airway smooth muscle it seems only 2 passive Ca2+ influx pathways are implicated, one sensitive to SKF 96365 (receptor gated Ca2+ channels) and the other to Ni2+ (store operated Ca2+ channels). Resting Ca2+ entry could provide a sufficient amount of Ca2+ and contribute to resting intracellular Ca2+ concentration ([Ca2+]i), maintenance of the resting membrane potential, myogenic tone, and sarcoplasmic reticulum-Ca2+ refilling. However, further research, especially in airway smooth muscle, is required to better explore the physiological role of this passive Ca2+ influx pathway as it could be involved in airway hyperresponsiveness.
Montaño
Luis M
LM
Departmento de Farmacología, Facultad de Medicina, UNAM, Ciudad Universitaria, CP 04510, México DF, México. lmmr@servidor.unam.mx
Bazán-Perkins
Blanca
B
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D006801:Humans; D008564:Membrane Potentials; D009130:Muscle, Smooth / Q000378:metabolism* / Q000502:physiology; D014132:Trachea / Q000378:metabolism*
D002118:Calcium