, Volume 83, Issue 3, pp 263-269
Date: 17 Dec 2008

Hormetic acute response and chronic effect of ethanol on adenine nucleotide hydrolysis in rat platelets

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Abstract

The objective of this study was to verify the acute and chronic effects of ethanol on platelet NTPDase and 5′-nucleotidase activities. These enzymes modulate platelet function by regulating adenine nucleotide bioavailability and adenosine production. In the acute treatment, doses of 0.8, 2.0, 4.0, 6.0 and 8.0 g/kg ethanol were administered via orogastric tube, and induced a biphasic or hormetic effect on ATP, ADP and AMP platelet hydrolysis. Ethanol at a dose of 0.8 and 2.0 g/kg increased NTPDase activity (44 and 35%, P < 0.0001) with ATP as substrate, whereas when ADP was used there was only a tendency for NTPDase activity to increase. ATP and ADP hydrolysis decreased by 31–77% (P < 0.0001) in 4.0, 6.0 and 8.0 g/kg of ethanol compared to the control. AMP hydrolysis showed a tendency to increase at ethanol doses of 0.8 and 2.0 g/kg, but was inhibited by 45–100% (P < 0.0001) at the higher doses. Chronic treatment consisted of the oral administration of 20% ethanol solution during 31 weeks as the only source of liquid and inhibited NTPDase activity (15 and 20%, P < 0.05) with ATP and ADP as substrate, respectively. However, AMP hydrolysis by 5′-nucleotidase increased by 40% (P < 0.05). Thus, we speculate that the effects of ethanol on NTPDase and 5′-nucleotidase activities could be related with the platelets alterations commonly observed in alcohol users.