卡巴胆碱对大鼠腮腺45Ca内流的刺激作用。

Stimulation of 45Ca influx in rat parotid gland by carbachol.

作者信息

Putney J W

出版信息

J Pharmacol Exp Ther. 1976 Dec;199(3):526-37.

Abstract

Secretion of alpha-amylase by rat parotid glands was stimulated by 10(-5) M carbachol when Ca was present in the bathing medium. The optimal Ca concentration was 1.0 mM in the absence of Mg ion. Lowering the extracellular Na to near one-half and one-quarter of normal levels produced a significant increase in carbachol-induced secretion. The metabolism of 45Ca by the slices could be described by three components of exchange. The faster two, with time constants of 4 and 16 minutes, each appeared to represent a mixture of free extracellular Ca and rapidly exchanging superficially bound Ca. Influx into the slower (tau = 78 minutes) component (apparently intracellular) was enhanced by 10(-5) M carbachol. This was apparent by standard flux techniques only in low (65 mM) Na solutions, but was readily discernible in normal Na (125 mM) with the "lanthanum-residual" technique. The increase in 45Ca influx due to carbachol resembles the secretory response to carbachol in being potentiated by low Na, blocked by 1.0 mM La, and blocked by 10(-4) M atropine. It was concluded on the basis of this and other evidence that the primary step in the induction of exocytosis by carbachol in the parotid gland is an increased influx of Ca.

摘要

当浴液中存在钙离子时，10⁻⁵ M 的卡巴胆碱可刺激大鼠腮腺分泌α淀粉酶。在无镁离子的情况下，最佳钙离子浓度为1.0 mM。将细胞外钠离子浓度降至正常水平的近二分之一和四分之一时，卡巴胆碱诱导的分泌显著增加。切片对⁴⁵Ca 的代谢可用三种交换成分来描述。较快的两种成分，时间常数分别为4分钟和16分钟，似乎各自代表游离细胞外钙和快速交换的表面结合钙的混合物。10⁻⁵ M 的卡巴胆碱可增强进入较慢成分（时间常数τ = 78分钟，显然是细胞内的）的钙离子内流。这仅在低钠（65 mM）溶液中通过标准通量技术才能明显看出，但使用“镧残留”技术在正常钠浓度（125 mM）下很容易辨别。卡巴胆碱引起的⁴⁵Ca 内流增加与对卡巴胆碱的分泌反应相似，即低钠可增强其反应，1.0 mM 的镧可阻断其反应，10⁻⁴ M 的阿托品也可阻断其反应。基于此及其他证据得出结论，卡巴胆碱在腮腺中诱导胞吐作用的主要步骤是钙离子内流增加。