论文部分内容阅读
用fura-2显微荧光法测量细胞内自由钙浓度[Ca~(2+)]_i,在单个大鼠胰腺β细胞上探讨了葡萄糖诱发的[Ca~(2+)]_i初期下降相(GIDP)、钙振荡和钙库释放的影响因素。实验中发现,非刺激浓度的葡萄糖(5 mmol/L)仍可导致β细胞特有的GIDP。GIDP与去极化无关,也不受外钙的影响,但能被内质网钙泵抑制剂thapsigargin抑制,提示此过程可能缘于钙库对胞浆Ca~(2+)的摄取。在胞内钙振荡过程中移去胞外液中的Ca~(2+),振荡会逐渐停止;若施加thapsigargin,钙振荡仍能继续维持,说明钙振荡主要缘于外钙内流,钙库在钙振荡维持中的作用不大。无外钙条件下,葡萄糖诱导的钙库释放能被钠通道阻断剂TTX所抑制,而高钾对钙库的释放作用却不受TTX的影响,这提示膜去极化可以直接诱导钙库释放。因此,细胞膜去极化、外钙内流、胞内钙库的摄取和释放共同协调着β细胞内的Ca~(2+)平衡。
The intracellular free calcium concentration [Ca ~ (2 +)] _i was measured by fura-2 microfluorescence method. The initial phase of [Ca ~ (2 +)] _i induced by glucose was investigated on a single rat pancreatic β cell GIDP), calcium oscillation and calcium release. Experiments found that non-stimulated concentrations of glucose (5 mmol / L) can still lead to β-cell-specific GIDP. GIDP has nothing to do with depolarization, nor external calcium, but can be inhibited by thapsigargin, an endoplasmic reticulum calcium pump inhibitor, suggesting that this process may be due to the uptake of cytoplasmic Ca 2+ by the calcium bank. In the process of intracellular calcium oscillation to remove Ca 2+ in extracellular fluid, the oscillation will gradually stop; if thapsigargin is applied, calcium oscillation can continue to maintain, indicating that calcium oscillation mainly due to the influx of calcium, calcium The role of calcium oscillation in the maintenance of little. In the absence of external calcium, glucose-induced calcium release was inhibited by the sodium channel blocker TTX, whereas release of calcium by high potassium was unaffected by TTX, suggesting that membrane depolarization can directly induce calcium stores freed. Therefore, cell membrane depolarization, extracellular calcium influx, and uptake and release of intracellular calcium stores coordinate the Ca 2+ balance in β cells.