Adenosine modulates the (Na++K+)ATPase activity in Malpighian tubules isolated from Rhodnius prolixus.

摘要

The role of adenosine on regulation of the (Na++K+)ATPase activity present in the Malpighian tubules isolated from Rhodnius prolixus was investigated. Adenosine decreases the (Na++K+) ATPase specific activity by 88%, in a dose-dependent manner, withmaximal effect at a concentration of 10-9 M. This effect was mimicked by N6-cyclohexyladenosine (CHA) at 10-8 M, an agonist for A1 adenosine receptor, and was reversed by 10-9 M 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), an antagonist for A1 adenosinereceptor. On the other hand, 5'-N-ethyl-carboxamide adenosine (NECA), an agonist for A2 adenosine receptor, used in the range of 10-9-10-5 M, did not change the (Na++K+)ATPase specific activity. In the same way, 10-8 M 3,7-dimethyl-1-propargylxanthine (DMPX), an antagonist for A2 adenosine receptor, did not modify the inhibitory effect of adenosine. These data suggest that the inhibitory effect of adenosine on the (Na++K+)ATPase specific activity present in Malpighian tubules from R. prolixus is mediated by A1 adenosine receptor activation.