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大鼠下颌下腺腺泡中细胞外ATP引起的Ca2+内流的动员,而非储存Ca2+的动员。

Mobilization of Ca2+ influx, but not of stored Ca2+, by extracellular ATP in rat submandibular gland acini.

作者信息

Hurley T W, Ryan M P, Shoemaker D D

机构信息

Departments of Child Health and Physiology, University of Missouri-Columbia, School of Medicine 65212.

出版信息

Arch Oral Biol. 1994 Mar;39(3):205-12. doi: 10.1016/0003-9969(94)90046-9.

Abstract

To determine its effect on cytosolic Ca2+ levels (Ca2+i) and to assess its role as an autonomic cotransmitter, ATP was added to suspensions of rat pancreatic or submandibular gland acini loaded with fura-2. ATP had no effect on pancreatic acinar Ca2+i at either high (2.5 mM) or low (< 10 nM) extracellular Ca2+ concentrations (Ca2+o). In submandibular acini, ATP had little effect on Ca2+i when Ca2+o was < 10 nM but, with Ca2+o equal to 2.5 mM, ATP increased Ca2+i to a steady-state level 2-4 times the resting level of 50-100 nM. Addition of carbachol or epinephrine further increased Ca2+i. The mean and standard deviation of the ATP4- concentration at half of maximal activity (K0.5 ATP4-) was 33 +/- 7 microM and the Hill coefficient was 1.5 +/- 0.7 (n = 9). The active species is apparently ATP4-, as adding Mg2+ increases the total concentration of ATP needed to elevate Ca2+i. GTP, UTP, ADP and adenosine produced no significant changes in Ca2+i. However, 3'-O-(4-benzoyl)benzoyl ATP (BZATP) increased Ca2+i with a K0.5 BZATP of 2.4 +/- 0.5 microM and a Hill coefficient of 2.8 +/- 0.4 (n = 8). ATP-induced changes in Ca2+i were not due to a generalized increase in acinar-cell permeability and were unaffected by voltage-dependent Ca2+ channel blockers or by the presence of depolarizing concentrations of K+.(ABSTRACT TRUNCATED AT 250 WORDS)

摘要

为了确定其对胞质钙离子水平(Ca2+i)的影响,并评估其作为自主神经共递质的作用,将ATP添加到装载有fura-2的大鼠胰腺或下颌下腺腺泡悬液中。在高(2.5 mM)或低(<10 nM)细胞外钙离子浓度(Ca2+o)下,ATP对胰腺腺泡Ca2+i均无影响。在下颌下腺腺泡中,当Ca2+o<10 nM时,ATP对Ca2+i影响很小,但当Ca2+o等于2.5 mM时,ATP将Ca2+i增加至稳态水平,为50 - 100 nM静息水平的2 - 4倍。添加卡巴胆碱或肾上腺素可进一步增加Ca2+i。最大活性一半时的ATP4-浓度(K0.5 ATP4-)的平均值和标准差为33±7 μM,希尔系数为1.5±0.7(n = 9)。活性物质显然是ATP4-,因为添加Mg2+会增加升高Ca2+i所需的ATP总浓度。GTP、UTP、ADP和腺苷对Ca2+i无显著影响。然而,3'-O-(4-苯甲酰)苯甲酰ATP(BZATP)可增加Ca2+i,其K0.5 BZATP为2.4±0.5 μM,希尔系数为2.8±0.4(n = 8)。ATP诱导的Ca2+i变化并非由于腺泡细胞通透性普遍增加,且不受电压依赖性钙离子通道阻滞剂或去极化浓度的K+存在的影响。(摘要截短于250字)

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