Hunter M, Smith P A, Case R M
Cell Calcium. 1983 Oct;4(4):307-17. doi: 10.1016/0143-4160(83)90007-6.
Acetylcholine-stimulated fluid secretion from the perfused rabbit mandibular salivary gland was inhibited in a biphasic manner when extracellular calcium concentration was reduced in the range 5 X 10(-4) - 10(-5)M. An initial rapid inhibition was followed by partial recovery to a plateau, the level of which depended upon the calcium concentration. Since no recovery was observed during substitution of calcium by strontium, recovery may depend upon an increased membrane permeability to calcium. It is concluded that acetylcholine evokes fluid secretion in this gland by enhancing calcium entry from the extracellular space, an action which can be mimicked by the calcium ionophore A23187. Changes in the electrolyte composition of saliva during calcium-depletion were such as to suggest that ductal reabsorption of sodium and chloride, and secretion of potassium are inhibited as extracellular calcium concentration is reduced. Secretin-stimulated fluid secretion from the cat pancreas was unaffected when perfusate calcium concentration was reduced to 2.5 X 10(-6)M and carbachol-stimulated amylase secretion was only slightly reduced. Since the latter is a calcium-dependent process, the source of calcium is presumably intracellular. In both glands, reducing calcium to 1 X 10(-6)M caused rapid and irreversible inhibition of fluid secretion.
当细胞外钙浓度在5×10⁻⁴ - 10⁻⁵M范围内降低时，乙酰胆碱刺激的灌注兔下颌下唾液腺的液体分泌受到双相抑制。最初是快速抑制，随后部分恢复到一个平台期，该平台期的水平取决于钙浓度。由于在用锶替代钙的过程中未观察到恢复，恢复可能取决于膜对钙的通透性增加。结论是，乙酰胆碱通过增强细胞外空间钙的内流来引起该腺体的液体分泌，钙离子载体A23187可以模拟这一作用。钙耗竭期间唾液电解质组成的变化表明，随着细胞外钙浓度降低，钠和氯的导管重吸收以及钾的分泌受到抑制。当灌注液钙浓度降低到2.5×10⁻⁶M时，促胰液素刺激的猫胰腺液体分泌不受影响，而卡巴胆碱刺激的淀粉酶分泌仅略有减少。由于后者是一个钙依赖过程，钙的来源可能是细胞内的。在这两种腺体中，将钙浓度降低到1×10⁻⁶M会导致液体分泌迅速且不可逆地受到抑制。
