Effect of L-Arginine on Na⁺,K⁺-ATPase Activity in Rat Aorta Endothelium

O. V. Akopova^*, O. N. Kharlamova, and G. L. Vavilova

Bogomolets Institute of Physiology, National Academy of Sciences of Ukraine, ul. Bogomoltsa 4, Kiev, 01024 Ukraine; fax: 256-2000; E-mail: circul@serv.biph.kiev.ua

^* To whom correspondence should be addressed.

Received September 27, 2001; Revision received April 26, 2002

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The effect of L-arginine on the Na⁺,K⁺-ATPase activity in rat aorta endothelium was studied at its physiological concentrations in the range of 10^-6-10^-3 M. The enzyme activity was 35.5% increased by low concentrations of L-arginine (<=10^-5 M) and its activity was 32.3-37.1% decreased at the L-arginine concentrations of 10^-4-10^-3 M. A similar inhibition (by 34.5-42.8%) was also found in the presence of a NO-donor nitroglycerol (10^-4-10^-3 M). An optical isomer of L-arginine, D-arginine, at the concentrations of <=10^-5 M also increased the enzyme activity by 37.1%, but its inhibiting effect was much less pronounced and was 15.7% at the D-arginine concentration of 10^-3 M. An inhibitor of NO-synthase, L-NAME (N^G-nitroarginine, methyl ester), failed to inhibit Na⁺,K⁺-ATPase. However, the presence of L-NAME abolished the inhibition of Na⁺,K⁺-ATPase by high concentrations of L-arginine. Thus, the effect of L-arginine on the endothelial Na⁺-pump depended on its concentration, and it is suggested that the enzyme inhibition by high concentrations of L-arginine should be associated with activation of the endogenous synthesis of NO.

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KEY WORDS: Na⁺,K⁺-ATPase, endothelium, aorta, L-arginine, NO

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