Alcohol abrogates intracellular Ca2+ elevation by angiotensin II and ATP in cultured rat astrocytes
Location
Georgia
Start Date
12-5-2015 1:00 PM
Description
Intracellular Ca2+ of astrocytes can be mobilized by many neurotransmitters and neuromodulators. We studied whether the regulation of intracellular Ca2+ concentration ([Ca2+]i) by angiotensin II and ATP is altered by alcohol treatment in cultured rat hippocampal astrocytes. Pulsatory [Ca2+]i elevation as measured by Fura-2 fluorescence can be repeatedly induced when the cells were challenged with Angiotensin II (30 nM) and ATP (3 µM) in the absence of ethanol. Peptidergic neurotransmitter angiotensin II produced a peak and a prolonged plateau elevation in [Ca2+]i. In comparison, purinergic neuromodulator ATP caused a brief and steeper Ca2+ peak with a much faster recovery phase (i.e., lack of prolonged plateau elevation of [Ca2+]i. Ethanol treatment (10 - 20 mM) of the cells for 5 to 10 min itself did not cause any detectable [Ca2+]i change. However, in the presence of alcohol (20 mM, approximately equal to 0.12% plasma alcohol level), both the peak and the plateau phases of [Ca2+]i elevation by angiotensin II (30 nM) and ATP (3 µM) were completely abolished. The ethanol intoxicated cells did not respond to higher concentration of angiotensin II (300 nM) but were able to generate a blunted [Ca2+]i elevation when challenged with 1 mM ATP. These results demonstrate that ethanol alters the regulation of [Ca2+]i by neurotransmitters and neuromodulators in astrocytes, which may play a significant role in alcohol intoxication.
Alcohol abrogates intracellular Ca2+ elevation by angiotensin II and ATP in cultured rat astrocytes
Georgia
Intracellular Ca2+ of astrocytes can be mobilized by many neurotransmitters and neuromodulators. We studied whether the regulation of intracellular Ca2+ concentration ([Ca2+]i) by angiotensin II and ATP is altered by alcohol treatment in cultured rat hippocampal astrocytes. Pulsatory [Ca2+]i elevation as measured by Fura-2 fluorescence can be repeatedly induced when the cells were challenged with Angiotensin II (30 nM) and ATP (3 µM) in the absence of ethanol. Peptidergic neurotransmitter angiotensin II produced a peak and a prolonged plateau elevation in [Ca2+]i. In comparison, purinergic neuromodulator ATP caused a brief and steeper Ca2+ peak with a much faster recovery phase (i.e., lack of prolonged plateau elevation of [Ca2+]i. Ethanol treatment (10 - 20 mM) of the cells for 5 to 10 min itself did not cause any detectable [Ca2+]i change. However, in the presence of alcohol (20 mM, approximately equal to 0.12% plasma alcohol level), both the peak and the plateau phases of [Ca2+]i elevation by angiotensin II (30 nM) and ATP (3 µM) were completely abolished. The ethanol intoxicated cells did not respond to higher concentration of angiotensin II (300 nM) but were able to generate a blunted [Ca2+]i elevation when challenged with 1 mM ATP. These results demonstrate that ethanol alters the regulation of [Ca2+]i by neurotransmitters and neuromodulators in astrocytes, which may play a significant role in alcohol intoxication.