Quinn S J, Williams G H, Tillotson D L
Department of Physiology, Boston University School of Medicine, MA 02118.
Proc Natl Acad Sci U S A. 1988 Aug;85(15):5754-8. doi: 10.1073/pnas.85.15.5754.
The cytosolic calcium (Ca2+i) response to angiotensin II (Ang II) was examined in single rat zona glomerulosa cells by monitoring fura-2 fluorescence with microspectrofluorimetry. Ang II concentrations ranged from 5 X 10(-12) to 5 X 10(-8) M. The mean peak Ca2+i increase was similar at all Ang II concentrations (205 +/- 11 nM), with a significant difference (P less than 0.05) found only between 5 X 10(-12) M (151 +/- 16 nM) and 5 X 10(-9) M (236 +/- 24 nM). Striking differences over the range of Ang II concentrations were found in the Ca2+i response kinetics. A dose-dependent delay of the onset of the Ca2+i response was observed ranging from 2.6 +/- 0.3 sec at 5 X 10(-8) M to 181 +/- 27 sec at 5 X 10(-12) M Ang II. After the delay, cells typically responded with an abrupt increase in Ca2+i, complete within 15 sec. At low Ang II concentrations (5 X 10(-11) and 5 X 10(-12) M), a complex response was often observed consisting of Ca2+i oscillations. Higher Ang II concentrations gave some evidence of Ca2+i oscillation, especially at 5 X 10(-10) M where oscillations appeared fused. Above 5 X 10(-10) M Ang II, the initial Ca2+i increase decayed to an apparent steady-state value 38-40% of the peak response within 5 min; 5 X 10(-10) M Ang II produced a smaller decline to 63% of the initial Ca2+i increase. In contrast to cell population studies, assessment of individual glomerulosa cells demonstrates (i) a dose-dependent delay prior to a rapid increase in Ca2+i; (ii) a similar peak increase at most Ang II concentrations; (iii) greater sensitivity of the Ca2+i response; and (iv) a complex oscillating Ca2+i response in the physiological range of Ang II.
通过显微分光荧光测定法监测fura - 2荧光，在单个大鼠肾小球旁细胞中检测了细胞溶质钙（Ca2 + i）对血管紧张素II（Ang II）的反应。Ang II浓度范围为5×10（-12）至5×10（-8）M。在所有Ang II浓度下，平均峰值Ca2 + i增加相似（205±11 nM），仅在5×10（-12）M（151±16 nM）和5×10（-9）M（236±24 nM）之间发现有显著差异（P <0.05）。在Ca2 + i反应动力学方面，在Ang II浓度范围内发现了显著差异。观察到Ca2 + i反应开始的剂量依赖性延迟，范围从5×10（-8）M时的2.6±0.3秒到5×10（-12）M Ang II时的181±27秒。延迟后，细胞通常会出现Ca2 + i的突然增加，并在15秒内完成。在低Ang II浓度（5×10（-11）和5×10（-12）M）下，经常观察到由Ca2 + i振荡组成的复杂反应。较高的Ang II浓度给出了一些Ca2 + i振荡的证据，特别是在5×10（-10）M时，振荡似乎融合在一起。在5×10（-10）M以上的Ang II浓度下，最初的Ca2 + i增加在5分钟内衰减至峰值反应的38 - 40％的表观稳态值；5×10（-10）M Ang II导致下降幅度较小，降至初始Ca2 + i增加的63％。与细胞群体研究相反，对单个肾小球旁细胞的评估表明：（i）在Ca2 + i快速增加之前存在剂量依赖性延迟；（ii）在大多数Ang II浓度下峰值增加相似；（iii）Ca2 + i反应的敏感性更高；（iv）在Ang II的生理范围内存在复杂的振荡Ca2 + i反应。
