Park T J, Lee I S, Ha H, Kim K T
Department of Life Science, Pohang University of Science and Technology, Korea.
Mol Cells. 1999 Feb 28;9(1):67-71.
The effects of temperature on ion fluxes and catecholamine secretion that are mediated by nicotinic acetylcholine receptors (nAChRs), voltage-sensitive calcium channels (VSCCs), and voltage-sensitive sodium channels (VSSCs) were investigated using bovine adrenal chromaffin cells. When the chromaffin cells were stimulated with DMPP, a nicotinic cholinergic agonist, or 50 mM K+, the intracellular calcium ([Ca2+]i) elevation reached a peak and decreased more slowly at lower temperatures. The DMPP-induced responses were more sensitive to temperature changes compared to high K+-induced ones. In the measurement of intracellular sodium concentrations ([Na+]i), it was found that nicotinic stimulation required a longer time to attain the maximal level of [Na+]i at lower temperatures. In addition, the VSSCs-mediated [Na+]i increase evoked by veratridine was also reduced as the temperature decreased. The measurement of [3H]norepinephrine (NE) secretion showed that the secretion within the first 3 min evoked by DMPP or high K+ was greatest at 37 degrees C. However, at 25 degrees C, the secretion evoked by DMPP, but not that by the 50 mM K+, was greater after 10 min of stimulation. This data suggest that temperature differentially affects the activity of nAChRs, VSCCs, and VSSCs, resulting in differential [Na+]i and [Ca2+]i elevation, and in the [3H]NE secretion by adrenal chromaffin cells.
利用牛肾上腺嗜铬细胞研究了温度对由烟碱型乙酰胆碱受体（nAChRs）、电压敏感性钙通道（VSCCs）和电压敏感性钠通道（VSSCs）介导的离子通量和儿茶酚胺分泌的影响。当用烟碱型胆碱能激动剂DMPP或50 mM K⁺刺激嗜铬细胞时，细胞内钙（[Ca²⁺]i）升高达到峰值，并且在较低温度下下降得更慢。与高钾诱导的反应相比，DMPP诱导的反应对温度变化更敏感。在测量细胞内钠浓度（[Na⁺]i）时发现，在较低温度下，烟碱型刺激达到[Na⁺]i最大水平所需的时间更长。此外，随着温度降低，藜芦碱诱发的VSSCs介导的[Na⁺]i增加也减少。[³H]去甲肾上腺素（NE）分泌的测量表明，DMPP或高钾在最初3分钟内诱发的分泌在37℃时最大。然而，在25℃时，刺激10分钟后，DMPP诱发的分泌增加，但50 mM K⁺诱发的分泌没有增加。这些数据表明，温度对nAChRs、VSCCs和VSSCs的活性有不同影响，导致细胞内[Na⁺]i和[Ca²⁺]i升高不同，以及肾上腺嗜铬细胞[³H]NE分泌不同。
