In single rat pancreatic βcells, using fura-2 microfluorometry to measure [Ca2+] response upon different stimuli, the ways of calcium regulation have been studied. When the extracellular calcium concentration was 2.5...In single rat pancreatic βcells, using fura-2 microfluorometry to measure [Ca2+] response upon different stimuli, the ways of calcium regulation have been studied. When the extracellular calcium concentration was 2.5 mmol/L, either 60 mmol/L KCI, 20 mmol/L D-glucose or 0.1 mmol/L tolbutamide induced increase in [Ca2+]. Such increase in [Ca2+] was absent when the same stimuli were applied under zero extracellular calcium. These results indicate that the increase of [Ca2+] is induced by the activation of voltage-dependent calcium channels in p celis. The manifold forms of [Ca2+] change induced by glucose imply that the effects of glucose are complex. 5 mmol/L caffeine or 5 mmol/L MCh increase the [Ca2+], which is independent of the external calcium, suggesting that [Ca2+] can be regulated by Ca2+ release from not only the IP3-sensitive but also the ryanodine sensitive calcium stores in p celis. The latency of Ca responses for IP3 pathway (5 s) is faster than that for ryanodine pathway (30 s), it is展开更多
文摘In single rat pancreatic βcells, using fura-2 microfluorometry to measure [Ca2+] response upon different stimuli, the ways of calcium regulation have been studied. When the extracellular calcium concentration was 2.5 mmol/L, either 60 mmol/L KCI, 20 mmol/L D-glucose or 0.1 mmol/L tolbutamide induced increase in [Ca2+]. Such increase in [Ca2+] was absent when the same stimuli were applied under zero extracellular calcium. These results indicate that the increase of [Ca2+] is induced by the activation of voltage-dependent calcium channels in p celis. The manifold forms of [Ca2+] change induced by glucose imply that the effects of glucose are complex. 5 mmol/L caffeine or 5 mmol/L MCh increase the [Ca2+], which is independent of the external calcium, suggesting that [Ca2+] can be regulated by Ca2+ release from not only the IP3-sensitive but also the ryanodine sensitive calcium stores in p celis. The latency of Ca responses for IP3 pathway (5 s) is faster than that for ryanodine pathway (30 s), it is
