Effects of purines and forskolin on haemolysis.

Effects of adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), and adenosine on the antihaemolytic action of procaine, and the effect of ATP on the antihaemolytic actions of lidocaine, dibucaine, tetracaine, pentobarbitone, and chlorpromazine were investigated in rat erythrocytes. The effects of adenosine and its analogues D-N6-phenylisopropyladenosine (D-PIA), L-N6-phenylisopropyladenosine (L-PIA), N6-cyclohexyladenosine (CHA), 2-chloroadenosine, and N6-methyladenosine, as well as the effects of cyclic-AMP (cAMP), dibutyryl cAMP, and forskolin on haemolysis were also investigated in rat erythrocytes. ATP, ADP, and AMP, but not adenosine, antagonized in a concentration-dependent manner the antihaemolytic action of procaine, and ATP was ineffective against the antihaemolytic actions of lidocaine, dibucaine, tetracaine, pentobarbitone, and chlorpromazine. Adenosine and its analogues, but not N6-methyladenosine, protected erythrocytes against hypotonic haemolysis in a concentration-dependent manner. The order of potencies was: D-PIA greater than CHA greater than L-PIA greater than adenosine greater than 2-chloroadenosine. The effect of adenosine on haemolysis was not prevented by theophylline, 8-phenyltheophylline, or 8-sulfophenyltheophylline. Dibutyryl cAMP, a stable analogue of cAMP, and forskolin, a specific activator of adenylate cyclase, mimicked the antihaemolytic action of adenosine. cAMP was less efficient than adenosine. Adenine nucleotides antagonized the antihaemolytic action of procaine, probably due to calcium-chelating properties. In contrast, adenine nucleosides have antihaemolytic properties. The possibility that the antihaemolytic effects of these substances relate to cAMP and/or to lipophilicity is discussed.