Paeoniflorin reverses guanethidine-induced hypotension via activation of central adenosine A1 receptors in Wistar rats

1. Intravenous injection of paeoniflorin, a glycoside purified from the root of Paeonia lactiflora a, reversed guanethidine-induced hypotension in Wistar rats. 2. Pretreatment with the adenosine A(1) receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine inhibited this effect of paeoniflorin in a dose-dependent manner. 3. The action of paeoniflorin was not modified by 8-(p-sulfophenyl)theophylline, the polar antagonist of the adenosine A(1) receptor, which is not able to enter the central nervous system. 4. We conclude that paeoniflorin can reverse guanethidine-induced hypotension via activation of adenosine A(1) receptors in the brain of Wistar rats.