The effects of lidocaine and procainamide on the sarcolemmal membrane high affinity cyclic AMP phosphodiesterase of rat myocardium.

The incubation of rat myocardial sarcolemmal membranes with 10(-4)M lidocaine or procainamide results in a decreased fluorescence polarization of the extrinsic probes (diphenylhexatriene and 12-anthroylstearate) and in the stimulation of the membrane-bound high affinity cyclic AMP phosphodiesterase activity (PDE). Lidocaine or procainamide do not contrast, but facilitate the aminophylline inhibitory action on the PDE activity, without modifying the basic molecular mechanism of the inhibitory action. The amplitudes of the effects described are inversely correlated to the temperature, being greater at the lower tested temperature (25 degrees greater than 30 degrees greater than 37 degrees C).

Hydrolyzing activities on cAMP in E. coli B cells incubated in the presence of polyamines.

1. Hydrolyzing activities on cAMP were investigated in E. coli B cells incubated in the presence or absence of 10(-5) M spermine, spermidine or putrescine. 2. Bacterial cells incubated in the presence of each of the investigated polyamines show an increase in the PDE (phosphodiesterase) activities already evident after 3 min of incubation, reaching the maximum between 5 and 10 min. disappearing between 15 and 25 min. 3. The stimulating effect is higher in the presence of lower (10(-6) M) substrate concentration (high affinity PDE activities). 4. Kinetic analyses carried out for the "high affinity" PDE activity, indicate that spermidine and putrescine are the most effective on increasing both the Vmax or the apparent Km. 5. Kinetic analysis carried out for the "low affinity" PDE activity, indicate that putrescine is the most active on increasing either the Vmax or the apparent Km and that spermine and spermidine have both quantitatively and qualitatively comparable effects. 6. Analyses, by TLC, of the products of the hydrolytic activities on cyclic AMP (5'-adenosine monophosphate (5'-AMP), adenosine, inosine) indicate that the incubation in the presence of each of three polyamines, results in an increase also of the 5' nucleotidase and adenosine deaminase activity.